TY - BOOK AU - Arnold, S.V. AU - Editor PY - 2007 BT - Chemical Physics Research Trends CY - Hauppauge, NY PB - Nova Science KW - Chemical physics, book ER - TY - BOOK AU - Davies, J.S. PY - 2006 BT - Amino Acids, Peptides and Proteins, 2006; Volume 35 CY - Cambridge, U.K. PB - Royal Society of Chemistry KW - Amino acids, book ER - TY - BOOK AU - Nikolaev, A.V. AU - Backinowsky, L. AU - Defaye, J. AU - Editors PY - 2007 BT - Special Issue: Synthesis and Structure of Glycans. [In: Carbohydr. Res., 2007; 342(3-4)] CY - Amsterdam, Netherlands PB - Elsevier KW - Glycans, book ER - TY - BOOK AU - Sherma, J. AU - Fried, B. AU - Editors PY - 2007 BT - Special Issue: Thin Layer Chromatography. [In: J. Liq. Chromatogr. Relat. Technol., 2007; 30(15)] CY - Philadelphia, PA PB - Taylor & Francis KW - Thin layer chromatography ER - TY - BOOK AU - Sykstra, C. AU - Thakkar, A.J. AU - Editors PY - 2007 BT - Special Issue: Computational Organic Chemistry. [In: Theochem., 2007; 811(1-3)] CY - Amsterdam, Netherlands PB - Elsevier KW - Computational organic chemistry, book ER - TY - BOOK AU - Toniolo, C. AU - Bruckner, H. AU - Editors PY - 2007 BT - Topical Issue Peptaibiotics. [In: Chem. Biodiversity, 2007; 4(6)] CY - Zurich, Germany PB - Helvetica Chimica Acta KW - Peptaibiotics, book ER - TY - BOOK AU - Wipf, P. AU - Editor PY - 2005 BT - Handbook of Reagents for Organic Synthesis: Reagents for High-Throughput Solid-Phase and Solution-Phase Organic Synthesis CY - Chichester, U.K. PB - John Wiley & Sons KW - Reagents, solid phase, book ER - TY - BOOK AU - Zaikov, G.E. AU - Kozlov, G.V. AU - Makitra, R.G. AU - Editors PY - 2006 BT - Theoretical and Practical Guide to Organic Physical Chemistry CY - Hauppauge, NY PB - Nova Science SP - 179 KW - Physical organic chemistry, book ER - TY - BOOK AU - Pirrung, M.C. AU - Editor PY - 2007 BT - The Synthetic Organic Chemists' Companion CY - Hoboken, NJ PB - John Wiley & Sons SP - 198 KW - Synthesis, book ER - TY - BOOK AU - Meyer, F. AU - Limberg, C. AU - Editors PY - 2007 BT - Organometallic Oxidation Catalysis. [In: Top. Organomet. Chem., 2007; 22] CY - Berlin, Germany PB - Springer SP - 253 KW - Organometallic oxidation catalysis, book ER - TY - BOOK AU - Tundo, P. AU - Perosa, A. AU - Zecchini, F. AU - Editors PY - 2007 BT - Methods and Reagents for Green Chemistry CY - Hoboken, NJ PB - John Wiley & Sons SP - 311 KW - Green chemistry, book ER - TY - BOOK AU - Zaikov, G.E. AU - Rakovsky, S.K. AU - Schiraldi, D.A. AU - Editors PY - 2006 BT - Diversity in Chemical Reactions: Pure and Applied Chemistry CY - Hauppauge, NY PB - Nova Science SP - 323 ER - TY - BOOK AU - Allen, D.W. AU - Tebby, J.C. AU - Editors PY - 2007 BT - Specialist Periodical Reports. [In: Organophosphorus Chem., 2007; 36] CY - Cambridge, U.K. PB - Royal Society of Chemistry SP - 336 KW - Organophosphorus chemistry, book ER - TY - BOOK AU - Richard, J.P. AU - Editor PY - 2006 BT - Advances in Physical Organic Chemistry, Volume 41 CY - San Diego, CA PB - Elsevier SP - 398 KW - Physical organic chemistry, book ER - TY - BOOK AU - Lindstrom, U.M. AU - Editor PY - 2007 BT - Organic Reactions in Water: Principles, Strategies and Applications CY - Oxford, U.K. PB - Blackwell Publishing SP - 405 KW - Aqueous organic reactions, book ER - TY - BOOK AU - Mikami, K. AU - Lautens, M. AU - Editors PY - 2007 BT - New Frontiers in Asymmetric Catalysis CY - Hoboken, NJ PB - John Wiley & Sons SP - 418 KW - Asymmetric catalysis, book ER - TY - BOOK AU - Bachrach, S.M. PY - 2007 BT - Computational Organic Chemistry CY - Hoboken, NJ PB - John Wiley & Sons SP - 478 KW - Computational organic chemistry, book ER - TY - BOOK AU - Yudin, A. AU - Editor PY - 2006 BT - Aziridines and Epoxides in Organic Synthesis CY - Weinheim, Germany PB - Wiley-VCH SP - 492 KW - Aziridines, book Epoxides, book ER - TY - BOOK AU - Laali, K.K. AU - Editor PY - 2007 BT - Recent Developments in Carbocation and Onium Ion Chemistry CY - Washington, DC PB - American Chemical Society SP - 528 KW - Carbocations, book Onium ions, book ER - TY - BOOK AU - Landgrebe, J.A. AU - Editor PY - 2005 BT - Theory and Practice in the Organic Laboratory: With Microscale and Standard Scale Experiments; 5th Edition CY - Belmont, CA PB - Thomson/Wadsworth SP - 538 KW - Microscale organic labs, book ER - TY - BOOK AU - Hall, D.G. AU - Editor PY - 2005 BT - Boronic Acids: Preparation and Applications in Organic Synthesis and Medicine CY - Weinheim, Germany PB - Wiley-VCH SP - 549 KW - Boronic acids, book ER - TY - BOOK AU - Overman, L.E. AU - Editor PY - 2007 BT - Organic Reactions, Volume 68 PB - John Wiley & Sons, Inc., Hoboken, N. J. SP - 552 ER - TY - BOOK AU - Mueller, T.J.J. AU - Bunz, U.H.F. AU - Editors PY - 2007 BT - Functional Organic Materials: Syntheses, Strategies and Applications CY - Weinheim, Germany PB - Wiley-VCH SP - 588 KW - Functional organic materials, book ER - TY - BOOK AU - Fassina, G. AU - Miertus, S. AU - Editors PY - 2005 BT - Combinatorial Chemistry and Technologies: Methods and Applications, Second Edition CY - Boca Raton, Florida PB - CRC Press SP - 597 KW - Combinatorial chemistry, book ER - TY - BOOK AU - Li, J.J. AU - Editor PY - 2007 BT - Name Reactions for Functional Group Transformations CY - Hoboken, NJ PB - John Wiley SP - 753 KW - Functional transformations, book ER - TY - BOOK AU - Kurti, L. AU - Czako, B. AU - Editors PY - 2005 BT - Strategic Applications of Named Reactions in Organic Synthesis CY - Burlington, MA PB - Academic Press SP - 864 KW - Named reactions, book ER - TY - BOOK AU - Denisov, E.T. AU - Afanas'ev, I.B. AU - Editors PY - 2005 BT - Oxidation and Antioxidants in Organic Chemistry and Biology CY - Boca Raton, Florida PB - CRC Press SP - 1024 KW - Oxidation, book Antioxidants, book ER - TY - BOOK AU - Warriner, S.L. AU - Editor PY - 2007 BT - Sciences of Synthesis. Compounds with Two Carbon - Heteratom Bonds CY - Stuttgart, Germany PB - Georg Thieme Verlag SP - 1286 KW - Synthesis, two heteroatoms, book ER - TY - JOUR AU - Maulide, N. AU - Vanherck, J.-C. AU - Gautier, A. AU - Marko, I.E. PY - 2007 TI - Mild and Neutral Deprotections Catalyzed by Cerium(IV) Ammonium Nitrate SP - 381-92 KW - Deprotection, cerium ammonium nitrate AB - A review. The development of a chemoselective, and catalytic deprotection methodol. that proceeds under mild and neutral conditions is described, and its mechanism of action is analyzed in some detail. The scope, limitations, and advantages of this protocol are discussed. Selected applications in synthesis are also highlighted. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Weng, Z. AU - Teo, S. AU - Hor, T.S.A. PY - 2007 TI - Metal Unsaturation and Ligand Hemilability in Suzuki Coupling SP - 676-84 KW - Suzuki catalysts, hemilabile ligands AB - A review. The combinative and complementary use of a hemilabile difunctional ligand on a metal, notably palladium, that is coordinatively and electronically unsatd. has led to the isolation of a string of unexpected low-valent complexes that are structurally intriguing. The ligands of interest are primarily ferrocenes functionalized by [P,N] and [P,O] donors. The characterization of these active Suzuki catalysts, which support sp2-sp2 couplings, give valuable insights into the key Suzuki intermediates such as those arising from the reductive elimination, transmetalation, and oxidative addn. steps. In this Account, we shall review and discuss our recent results in relation to selected developments in other labs. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Miyata, M. AU - Tohnai, N. AU - Hisaki, I. PY - 2007 TI - Crystalline Host-Guest Assemblies of Steroidal and Related Molecules: Diversity, Hierarchy, and Supramolecular Chirality SP - 694-702 KW - Steroids, host-guest assemblies AB - A review. Steroidal bile acids and over 50 of their derivs. serve as the hosts of inclusion crystals. These hosts each exhibit their own characteristic inclusion behaviors, which have been explored through more than 300 crystallog. data. The mols. with three-axial chirality combine in asym. fashion to form diverse assemblies, which have supramol. properties, such as recognition and dynamics, through cooperative weak interactions. From an overview of these results, an analogy emerged: the steroidal assemblies may have hierarchical structures, such as primary, secondary, tertiary, and host-guest assemblies, similar to proteins. Accordingly, the assemblies with dimensionality bear supramol. chirality, such as three-axial, tilt, helical, bundle, and complementary chirality. Such a concept can be extended to other org. substances, such as alkaloids and org. salts. These results move in the direction of supramol. crystal engineering. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Stevenson, C.D. PY - 2007 TI - Annulenylenes, Annulynes, and Annulenes SP - 703-11 KW - Annulynes Annulenes Annulenylenes AB - A review. A no. of techniques have been found to generate annulynes. Some of the annulynes have been found to spontaneously dimerize to biannulenylenes and to form triannulenylenes. The reaction products, thermodn., and kinetic stabilities of the annulenylenes, annulynes, and their parent annulenes prove to be extremely dependent upon the no. of .p. electrons. In fact, the addn. of an extra electron can trap some "fugitive" systems and render them sufficiently stable for spectroscopic study. Even the no. of neutrons can perturb the conjugation and, presumably, the stability of annulenes that have internal protons. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Waterman, R. AU - Hayes, P.G. AU - Tilley, T.D. PY - 2007 TI - Synthetic Development and Chemical Reactivity of Transition-Metal Silylene Complexes SP - 712-9 KW - Silylene complexes Silylene ligands AB - A review. A variety of transition-metal complexes with terminal silylene ligands have become available in recent years because of the discovery of several preparative methods. In particular, three general synthetic routes to these complexes have emerged, on the basis of anionic group abstraction, coordination of a free silylene, and .a.-hydrogen migration. The direct transformation of organosilanes to silylene ligands at a metal center (silylene extrusion) has also been obsd., and this has further spurred the exploration of silylenes as ligands. This Account describes the synthetic development of silylene ligands in our lab. and resulting investigations of stoichiometric and catalytic chem. for these species. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Moakes, G. AU - Janata, J. PY - 2007 TI - Slow Solvation Dynamics of a Water-Nitrobenzene System SP - 720-8 KW - Nitrobenzene-water system AB - A review. Very slow changes in solvation taking place in water-satd. nitrobenzene have been obsd. and studied by NMR, Fourier transform IR, and inelastic neutron scattering spectroscopy. These changes are most likely caused by the rearrangement of the hydrogen-bonded water network. Lithium salts used as the "reporter" species in the 7Li NMR expts. accelerate this reorganization. Results of this work are important for electrochem. studies of the nitrobenzene-water interface. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Vogel, P. AU - Turks, M. AU - Bouchez, L. AU - Markovic, D. AU - Varela-Alvarez, A. AU - Sordo, J.A. PY - 2007 TI - New Organic Chemistry of Sulfur Dioxide SP - 931-42 KW - Sulfur dioxide Sultines, from 1,3-dienes Sulfones, from dienes AB - A review. Simple 1,3-dienes undergo highly stereoselective hetero-Diels-Alder addns. with SO2 at low temp. giving sultines. These reactions are faster than the more exothermic cheletropic addns. of SO2-producing sulfolenes. This has led to the invention of a new C-C bond-forming reaction combining electron-rich dienes and alkenes with SO2. The reaction cascade has been exploited to develop combinatorial, one-pot, four-component syntheses of polyfunctional sulfones, sulfonamides, and sulfonic esters. It also allows us to generate, in one-pot operations, enantiomerically enriched polypropionate fragments contg. up to three contiguous stereogenic centers and a (E)-alkene unit. These fragments can be used directly in further C-C bond-forming reactions, such as cross-aldol condensations, thus permitting the expeditious construction of complicated natural products of biol. interest (e.g., Baconipyrones, Rifamycin S, Apoptolidinone) and analogs. New ene reactions of SO2 have also been discovered; they open new avenues to org. synthesis. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Juaristi, E. AU - Cuevas, G. PY - 2007 TI - Manifestations of Stereoelectronic Interactions in 1J C-H One-Bond Coupling Constants SP - 961-70 KW - C-H bond coupling constants AB - A review. Two-electron/two-orbital hyperconjugative interactions depend on the relative orientation of bonds and lone pairs in a mol. and are also inversely proportional to the energy difference between the interacting orbitals. Spectroscopic manifestations of stereoelectronic interactions are particularly useful exptl. signatures of these effects which can be utilized for testing mol. models. Empirical observations together with theor. interpretations in cyclohexane and six-membered heterocycles confirm the relevance of .s.C-Hax ? .s.*C-Hax nX ? .s.*C-Hax (X = O or N), .s.C-S ? .s.*C-Heq .b.-nO? .s.*C-Heq, .s.C(2)-Hax ? .p.*Cy (Y = O, S, or CH2), and .s.C(2)-Hax ? .s.*S-Oax two-electron/two-orbital stereoelectronic interactions that weaken the acceptor (or donor) C-H bonds and attenuate the Fermi contribution to the one-bond 13C-1H coupling consts. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Rayabarapu, D.K. AU - Cheng, C.-H. PY - 2007 TI - New Catalytic Reactions of Oxa- and Azabicyclic Alkenes SP - 971-983 KW - Azabicyclic alkenes Oxabicyclic alkenes Azabenzonorbornadienes Oxobenzonorbornadienes AB - A review. Bicyclic alkenes, including oxa- and azabenzonorbornadienes and their derivs., can be readily activated by transition metal complexes face-selectively due to their unsym. bicyclic structure and the intrinsic angle strain on the carbon-carbon double bond. We have developed several stereo-, regio-, and chemoselective reactions catalyzed by nickel and palladium complexes using these bicyclic alkenes as substrates, providing a unique means of constructing a variety of synthetically useful carbocycles and heterocycles with high efficiency not generally accessible by traditional methods. This Account outlines these new metal-catalyzed reactions that include couplings, cycloaddns., and cyclization reactions. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Bleeke, J.R. PY - 2007 TI - Aromatic Iridacycles SP - 1035-47 KW - Iridacycles, aromatic Aromatic metallacycles AB - A review. The 1st example of a family of related arom. metallacycles was synthesized, and the phys. and chem. properties of its individual members were studied. The metallacyclic rings in these compds. are, in general, constructed from pentadienyl- or heteropentadienyliridium precursors via C-H bond activation processes. The mols. display the structural and spectroscopic features of aromaticity, including ring planarity, .p.-bond delocalization, and diamagnetic ring current effects. The reactivity profile of the mols. is complex, reflecting the simultaneous presence of an arom. ring and a reactive metal center. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Ishihara, K. AU - Fushimi, M. AU - Akakura, M. PY - 2007 TI - Rational Design of Minimal Artificial Diels-Alderases Based on the Copper(II) Cation-Aromatic .p. Attractive Interaction SP - 1049-55 KW - Diels-Alderases Acylpyrazoles, Diels-Alderases AB - A review discusses the research of the Ishihara group on enantioselective Diels-Alder and Michael addn. reactions of acylpyrazoles using the copper(II) complex of an L-DOPA amide as an artificial Diels-Alderase; catalyst formation is driven by cation-.p. interactions between the copper and the arom. group of the L-DOPA amide. JO - Accounts of Chemical Research VL - 40 ER - TY - JOUR AU - Marion, N. AU - Diez-Gonzalez, S. AU - Nolan, S.P. PY - 2007 TI - N-Heterocyclic Carbenes as Organocatalysts SP - 2988-3000 KW - Carbenes, N-heterocyclic, organocatalysts AB - This review details the ever-increasing no. of reactions that can be promoted by N-heterocyclic carbenes. Organocatalyzed reaction represent an attractive alternative to metal-catalyzed processes notably because of their lower cost and benign environmental impact in comparison to organometallic catalysis. In this context, N-heterocyclic carbenes (NHCs) have been studied for their ability to promote primarily the benzoin condensation. Lately, dramatic progress in understanding their intrinsic properties and in their synthesis have made them available to org. chemists. This has resulted in a tremendous increase of their scope and in a true explosion of the no. of papers reporting NHC-catalyzed reactions. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Ohki, Y. AU - Fryzuk, M.D. PY - 2007 TI - Dinitrogen Activation by Group 4 Metal Complexes SP - 3180-3 KW - Dinitrogen bond activation AB - A review. When dinitrogen bridges two Group 4 metal centers in the side-on binding mode, the reactivity of the N2 unit is enhanced, as evidenced by unprecedented reactions with H2, alkynes, silanes, isocyanates, and now carbon dioxide. This Highlight summarizes a no. of recent breakthroughs in dinitrogen functionalization by bimetallic Group 4 complexes, culminating with the reaction of CO2 with a dihafium dinitrogen deriv. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Willis, M.C. PY - 2007 TI - Palladium-Catalyzed Coupling of Ammonia and Hydroxide with Aryl Halides: The Direct Synthesis of Primary Anilines and Phenols SP - 3402-4 KW - Anilines, direct synthesis Phenols, direct synthesis AB - A review. Back to basics: Ligand design has allowed two longstanding limitations of Pd-catalyzed C-N and C-O coupling reactions to be overcome. The use of specific sterically demanding electron-rich phosphine ligands makes it possible for ammonia and potassium hydroxide to act as coupling partners in palladium-catalyzed coupling with aryl halides. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Kunz, D. PY - 2007 TI - Synthetic Routes to N-Heterocyclic Carbene Complexes: Pyridine-Carbene Tautomerizations SP - 3405-8 KW - Carbenes, N-heterocyclic Pyridine, 2-carbene AB - A review. 70 Years ago the existence of the 2-carbene isomer of pyridine, which arises by pyridine-carbene tautomerization, was postulated. Now it has been prepd. from pyridine as a stable carbene complex by metal-induced C-H activation. This pyridine-carbene tautomerization is described and discussed along with other analogous carbene tautomerization reactions. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Fuerstner, A. AU - Davies, P.W. PY - 2007 TI - Catalytic Carbophilic Activation: Catalysis by Platinum and Gold .P. Acids SP - 3410-49 KW - Platinum catalysts Gold catalysts AB - A review. The ability of platinum and gold catalysts to effect powerful atom-economic transformations has led to a marked increase in their utilization. The quite remarkable correlation of their catalytic behavior with the available structural data, coordination chem., and organometallic reactivity patterns, including relativistic effects, allows the underlying principles of catalytic carbophilic activation by .p. acids to be formulated. The spectrum of reactivity extends beyond their utility as catalytic and benign alternatives to conventional stoichiometric .p. acids. The resulting reactivity profile allows this entire field of catalysis to be rationalized, and brings together the apparently disparate electrophilic metal carbene and nonclassical carbocation explanations. The advances in coupling, cycloisomerization, and structural reorganization - from the design of new transformations to the improvement to known reactions - are highlighted in this Review. The application of platinum- and gold-catalyzed transformations in natural product synthesis is also discussed. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Mihovilovic, M.D. AU - Stanetty, P. PY - 2007 TI - Metal-assisted Multicomponent Reactions Involving Carbon Monoxide - Towards Heterocycle Synthesis SP - 3612-5 KW - Heterocycles, via CO AB - A review. An assembly line for heterocycles: Multicomponent reactions have become a highly valuable tool for the generation of compd. libraries particularly of heterocyclic drug candidates. In particular, metal-assisted transformations have enabled the further extension of established methods and development of new strategies. This Highlight presents some innovative examples in which carbon monoxide is used to generate diverse heterocycles. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Butenschoen, H. PY - 2007 TI - A New Oxocarbon C12O6 via Highly Strained Benzyne Intermediates SP - 4012-4 KW - Benzynes AB - A review. Elimination of triflate followed by [2 + 2] cycloaddn. with ketene silyl acetals facilitates the formation of highly strained benzynes with one or two annulated cyclobutane rings. A prominent example based on this chem. is the synthesis of the novel oxocarbon C12O6 (I). JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Chianese, A.R. AU - Lee, S.J. AU - Gagne, M.R. PY - 2007 TI - Electrophilic Activation of Alkenes by Platinum(II): So Much More Than a Slow Version of Palladium(II) SP - 4042-59 KW - Alkenes, Pt activation AB - This review concerns platinum-catalyzed electrophilic alkene activation reaction initiated by addn. to the C=C bonds with protic carbon, nitrogen, oxygen, and phosphorus nucleophiles, as well as alkene or arene nucleophiles. The review specially emphasizes on the differences between platinum and palladium catalysts and proves that platinum-catalyzed reactions are often complementary to palladium catalysis. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Schreiner, P.R. PY - 2007 TI - Relative Energy Computations with Approximate Density Functional Theory - A Caveat! SP - 4217-9 KW - Density functional theory AB - A review. Not so simple: Common and broadly used d. functional theory (DFT) implementations do not properly account for medium-range electron correlation. The resultant errors in energy calcns., for example, for simple hydrocarbon isomers, can be large and increase with increasingly larger structures. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Ritch, J.S. AU - Chivers, T. PY - 2007 TI - Silicon Analogues of Crown Ethers and Cryptands: A New Chapter in Host-Guest Chemistry? SP - 4610-3 KW - Crown ethers, siloxane- Cryptands, siloxane AB - A review of alkali-metal complexes of siloxane-based crown ethers and cryptands. These findings have implications in the areas of host-guest chem., inorg. ring transformations, and ring-opening polymn. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Masson, G. AU - Housseman, C. AU - Zhu, J. PY - 2007 TI - The Enantioselective Morita-Baylis-Hillman Reaction and its Aza Counterpart SP - 4614-28 KW - Morita-Baylis-Hillman reaction AB - This review summarizes recent mechanistic insights and advances in the design and synthesis of small org. mol. catalysts for enantioselective MBH and aza-MBH reactions. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Welzel, P. PY - 2007 TI - A Long Research Story Culminates in the First Total Synthesis of Moenomycin A SP - 4825-9 KW - Moenomycin, synthesis AB - A review. The highly active inhibitor of the "forgotten" transglycosylases, moenomycin A, succumbed to total synthesis. The pentasaccharide backbone was constructed employing sulfoxides as glycosyl donors. The recent moenomycin results should establish it as a promising lead structure for new antiinfectives. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Herbert, D.E. AU - Mayer, U.F.J. AU - Manners, I. PY - 2007 TI - Strained Metallocenophanes and Related Organometallic Rings Containing .p.-Hydrocarbon Ligands and Transition-Metal Centers SP - 5060-81 KW - Metallocenophanes, strained Metallopolymers AB - A review. The structures, bonding, and ring-opening reactions of strained cyclic carbon-based mols. form a key component of std. textbooks. In contrast, the study of strained organometallic mols. contg. transition metals is a much more recent development. A wealth of recent research has revealed fascinating nuances in terms of structure, bonding, and reactivity. Building on initial work on strained ferrocenophanes, a broad range of strained organometallic rings composed of a variety of different metals, .p.-hydrocarbon ligands, and bridging elements has now been developed. Such strained species can potentially undergo ring-opening reactions to functionalize surfaces and ring-opening polymn. to form easily processed metallopolymers with properties detd. by the presence of the metal and spacer. This review summarizes the current state of knowledge on the prepn., structural characterization, electronic structure, and reactivity of strained organometallic rings with .p.-hydrocarbon ligands and d-block metals. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Korth, H.-G. PY - 2007 TI - Carbon Radicals of Low Reactivity Against Oxygen: Radically Different Antioxidants SP - 5274-6 KW - Radicals, carbon-centered Antioxidants, carbon radicals AB - A review. Carbon-centered radicals, which exist in thermal equil. with their dimers in soln., show unexpectedly low reactivity with mol. oxygen. Nevertheless their high reactivity with peroxyl radicals makes them a promising new class of chain-breaking antioxidants. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Cravotto, G. AU - Cintas, P. PY - 2007 TI - Forcing and Controlling Chemical Reactions with Ultrasound SP - 5476-8 KW - Ultrasound, benzocyclobutene polymers AB - A review. The collapse of sound bubbles induces mech. stress that can be transmitted to a target single bond by means of mechanosensitive polymers attached to the two sides of a benzocyclobutene. As surprising as it may be, ultrasound guides mols. into forbidden pathways by promoting the formation of only one isomer regardless of the starting benzocyclobutene. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Steven, A. AU - Overman, L.E. PY - 2007 TI - Total Synthesis of Complex Cyclotryptamine Alkaloids: Stereocontrolled Construction of Quaternary Carbon Stereocenters SP - 5488-508 KW - Alkaloids, cyclotryptamine AB - A review. Filling the void: Efficient and flexible syntheses of many complex cyclotryptamine alkaloids are now possible because of the development of a set of stereocontrolled methods for accessing their multiple quaternary carbon stereocenters. The key steps include a cascade of Heck reactions or asym. dialkylation followed by an asym. Heck reaction. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Gademann, K. AU - Bonazzi, S. PY - 2007 TI - Total Synthesis of Complex Cyanobacterial Alkaloids Without Using Protecting Groups SP - 5656-8 KW - Alkaloids, cyanobacterial AB - A review. The marine alkaloids hapalindole U, ambiguine, fischerindole, and welwitindolinone were synthesized without using any protecting groups. In an elegant approach the intrinsic reactivity of the sensitive isonitrile group was utilized instead to establish the mol. skeleton. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Schmuck, C. PY - 2007 TI - Guest Encapsulation Within Self-Assembled Molecular Containers SP - 5830-3 KW - Encapsulation Molecular containers, self-assembled AB - A review. Mol. hospitality: Self-assembled mol. containers provide a very specific geometric as well as chem. environment for a bound guest, which allows for selective guest binding or the stabilization of unstable mols. or unstable conformations within the capsule (see scheme). The geometric constraints imposed by the container can even change the outcome of a chem. reaction. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Ludwig, R. AU - Kragl, U. PY - 2007 TI - Do We Understand the Volatility of Ionic Ligands? SP - 6582-4 KW - Ionic liquids AB - A review. The volatile nature of ionic liqs.: Ionic liqs. are recognized as "green" solvents because of their essentially null volatility. Ironically, it is the low vapor pressure, the large enthalpy of vaporization, and the high b.p. of ionic liqs. that make it difficult to study their macroscopic behavior at a mol. level. Recent studies, however, have shed light on their thermochem. properties. JO - Angewandte Chemie, International Edition VL - 46 ER - TY - JOUR AU - Wheate, N.J. PY - 2006 TI - Cucurbit[n]uril: A New Molecule in Host-Guest Chemistry SP - 354 KW - Cucurbituril Anticancer agents, encapsulation Glycoluril, with formaldehyde AB - A review. Cucurbit[n]uril [n = 5-8, 10] is made from the condensation of glycoluril and formaldehyde in acid solns.; this article examines some of the important host-guest applications of cucurbit[n]urils in chem. and biochem. : entrapment of gases, pollutants, and other mols., encapsulation of anticancer agents, etc. JO - Australian Journal of Chemistry VL - 59 ER - TY - JOUR AU - Zard, S.Z. PY - 2006 TI - The Genesis of the Reversible Radical Addition-Fragmentation-Transfer of Thiocarbonylthio Derivatives from the Barton-Mccombie Deoxygenation: a Brief Account and Some Mechanistic Observations SP - 663-8 KW - Xanthates, transfer Thiocarbonylthio transfer AB - A review. The observations and reasoning leading to the discovery of the degenerative transfer of xanthates and related thiocarbonylthio derivs. are briefly reviewed. A few synthetic applications are presented, and the consequences on the emergence of the RAFT and MADIX polymn. technologies as well as some mechanistic aspects are briefly discussed. JO - Australian Journal of Chemistry VL - 59 ER - TY - JOUR AU - Vederas, J.C. PY - 2006 TI - 2005 Alfred Bader Award Lecture. Diaminopimelate and Lysine Biosynthesis - An Antimicrobial Target in Bacteria SP - 1197-207 KW - Diaminopimelate biosynthesis Lysine biosynthesis AB - A review. The development of bacterial resistance to current antibiotic therapy has stimulated the search for novel antimicrobial agents. The essential peptidoglycan cell wall layer in bacteria is the site of action of many current drugs, such as .b.-lactams and vancomycin. It is also a target for a no. of very potent bacterially produced antibiotic peptides, such as nisin A and lacticin 3147, both of which are highly posttranslationally modified lantibiotics that act by binding to lipid II, the peptidoglycan precursor. Another set of potential targets for antibiotic development are the bacterial enzymes that make precursors for lipid II and peptidoglycan, for example, those in the pathway to diamino pimelic acid (DAP) and its metabolic product, L-lysine. Among these, DAP epimerase is a unique nonpyridoxal phosphate (PLP) dependent enzyme that appears to use two active site thiols (Cys73 and Cys217) as a base and an acid to deprotonate the .a.-hydrogen of LL-DAP or meso-DAP from one side and reprotonate from the other. This process cannot be easily duplicated in the absence of the enzyme. A primary goal of our work was to generate inhibitors of DAP epimerase that would accurately mimic the natural substrates (meso-DAP and LL-DAP) in the enzyme active site and, through crystallog. anal., provide insight into mechanism and substrate specificity. A series of aziridine-contg. DAP analogs were chem. synthesized and tested as inhibitors of DAP epimerase from Haemophilus influenzae. Two diastereomers of 2-(4-amino-4-carboxybutyl)aziridine-2- carboxylic acid (AziDAP) act as rapid irreversible inactivators of DAP epimerase; the AziDAP analog of LL-DAP reacts selectively with the sulfhydryl of Cys73, whereas the corresponding analog of meso-DAP reacts with Cys217. AziDAP isomers are too unstable to be useful antibiotics. However, mass spectral and X-ray crystallog. analyses of the inactivated enzymes confirm that the thiol attacks the methylene group of the aziridine with concomitant ring opening to give a DAP analog bound in the active site. Further crystallog. analyses should yield useful mechanistic insights. JO - Canadian Journal of Chemistry VL - 84 ER - TY - JOUR AU - Kuehl, O. PY - 2007 TI - The Natural Bite Angle - Seen From a Ligand's Point of View SP - 230-8 KW - Ligands, natural bite angle AB - A review. The natural bite angle concept is examd. using N,N'-bisphosphino urea ligands as rigid scaffolds. The ligand has an upper limit of about 95° for the obsd. bite angle in chelate complexes, but prefers a much lower one. The ligand can be described as possessing downward flexibility. The dependence of the bite angle on the P-P distance within the ligand and the M-P bond length is illustrated. The metal tries to force the ligand into its own preferred structure, whereas the ligand wants to achieve a short P-P distance. A truly rigid ligand such as the N,N'-bisphosphino urea family is thus seen to clearly discriminate between metal atoms according to their individual assertiveness, using the P-P distance in the complex as a measure. Although the natural bite angle concept is valid and helpful in detg. the possible bite-angle range for ligands before it is actually synthesized, its practical applicability seems to be limited to those cases where the flexibility range of the ligand allows for only one metal-preferred bite angle to be realized. JO - Canadian Journal of Chemistry VL - 85 ER - TY - JOUR AU - Zon, G. PY - 2007 TI - Commercialization of Automated RNA Synthesis - Twenty Years On SP - 257-60 KW - RNA synthesis, automated AB - This review account provides a personal view of how ABI collaborated with Professor Kelvin K. Ogilvie in 1986 to commercialize automated RNA synthesis, using the 2'-O-alkylsilyl-protected monomers that he pioneered. Following the introduction of the first successful automated DNA synthesizer by Applied Biosystems Inc (ABI) in 1983, the company was in a position to consider the commercialization of addnl. chemistries to enable the automated synthesis of RNA oligonucleotides or other analogs. The influence of end-user scientific applications on this decision-making process is highlighted, together with the influence of such applications on subsequent commoditization of RNA. Hopefully, these perspectives will provide chemists with further appreciation of the sometime complex and unpredictable interplay between academically interesting chem. and evolving scientific applications that influence commercialization, and vice versa. JO - Canadian Journal of Chemistry VL - 85 ER - TY - JOUR AU - Lopez Ortiz, F. AU - Iglesias, M.J. AU - Fernandez, I. AU - Andujar Sanchez, C.M. AU - Ruiz Gomez, G. PY - 2007 TI - Nucleophilic Dearomatizing (DNAr) Reactions of Aromatic C,H-Systems. A Mature Paradigm in Organic Synthesis SP - 1580-691 KW - Dearomatization, nucleophilic AB - A review. This review encompasses dearomatization reactions promoted by nucleophilic addn. to arom. hydrocarbons excluding transition metal temporarily coordinated .p.-systems. Processes leading to isolable dearomatized products through the combined sequence of nucleophilic dearomatization-electrophilic trapping reactions are discussed. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Gibson, V.C. AU - Redshaw, C. AU - Solan, G.A. PY - 2007 TI - Bis(imino)pyridines: Surprisingly Reactive Ligands and a Gateway to New Families of Catalysts SP - 1745-76 KW - Bis(imino)pyridines Bis(imines) AB - A review. Use of bis(imino)pyridines and related bis(imines) as ligands and their assocd. metal complexation chem. are reviewed. While use of bis(imino)pyridines as supporting ligands for olefin polymn. catalysts was the focus of this review, recent efforts have seen its potential exploited as an anchoring ligand for other catalytic processes (e.g., asym. Diels-Alder, hydrosilyation, Mukaiyama aldol, cyclopropanation, hydrogenation, and cross-coupling reactions) and for metal-based activation of small mols. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Arjona, O. AU - Gomez, A.M. AU - Lopez, J.C. AU - Plumet, J. PY - 2007 TI - Synthesis and Conformational and Biological Aspects of Carbasugars SP - 1919-2036 KW - Carbasugars Aminocarbasugars Carbaoligosaccharides AB - This review presents the synthesis, conformational and biol. activities of carbasugars, aminocarbasugars, carbaoligosaccharides and carbasugar analogs. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Akhrem, I. AU - Orlinkov, A. PY - 2007 TI - Polyhalomethanes Combined with Lewis Acids in Alkane Chemistry SP - 2037-79 KW - Polyhalomethanes AB - A review. New aprotic superelectrophiles, which are the topic of this review, offer unique possibilities for the application of alkanes and cycloalkanes in org. synthesis. The matter concerns polyhalomethanes combined with Lewis acids. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Singh, G.S. AU - D'Hooghe, M. AU - De Kimpe, N. PY - 2007 TI - Synthesis and Reactivity of C-Heteroatom-Substituted Aziridines SP - 2080-135 KW - Aziridines, substituted AB - A review. Methods for the synthesis of C-heteroatom (oxygen, halogens, nitrogen, sulfur, phosphorus, and silicon) substituted aziridines and their reactivity are reviewed. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Walsh, P.J. AU - Li, H. AU - de Parrodi, C.A. PY - 2007 TI - A Green Chemistry Approach to Asymmetric Catalysis: Solvent-Free and Highly Concentrated Reactions SP - 2503-45 KW - Green chemistry, asymmetric AB - A review. This review covers small mol. catalyzed enantioselective reactions under solvent-free or highly concd. reaction conditions up to the end of 2006. Also included are reactions of enantioenriched substrates with enantioselective catalysts in which the diastereoselectivity is catalyst controlled (not substrate controlled). JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Parvulescu, V.I. AU - Hardacre, C. PY - 2007 TI - Catalysis in Ionic Liquids SP - 2615-65 KW - Ionic liquids AB - A review. Large increases in reactivity and selectivity have been achieved using IL medium for homogeneously catalyzed reactions, and in some cases, reactions have been demonstrated to only work in the ionic environment and not in the mol. solvents. While similar remarks can also be attributed to heterogeneously catalyzed reactions, the depth of study has not yet been achieved for trends to be easily identified. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Fagnoni, M. AU - Dondi, D. AU - Ravelli, D. AU - Albini, A. PY - 2007 TI - Photocatalysis for the Formation of the C-C Bond SP - 2725-56 KW - Photocatalysis, C-C bond formation AB - A review. The potential that photocatalysis has for the development of green methods for the formation of the C-C bond are reviewed. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Kar, M. AU - Basak, A. PY - 2007 TI - Design, Synthesis, and Biological Activity of Unnatural Enediynes and Related Analogues Equipped with pH-Dependent or Phototriggering Devices SP - 2861-90 KW - Enediynes AB - A review. The synthesis and reactivity of unnatural enediynes and related mols. equipped with pH-dependent or photoirradn.-triggering devices are reviewed. The strategies adapted for pH-based triggering include activation through enediyne to enyne-cumulene conversion, activation through acid- or base-catalyzed ring opening, activation through salt formation, activation through acid-catalyzed keto-enol tautomerism, in situ generation of enediynes through allylic rearrangement/.b.- elimination, and base-catalyzed intramol. transannular reaction (for macrocycles). Approaches to phototriggering are based on use of enediynes activated towards photo-Bergman cyclization, activation of enediynes via photoinduced electron transfer, photoexcitation of enediyne metal complexes, photoisomerization of azobenzene-based enediynes, etc. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Rubin, M. AU - Rubina, M. AU - Gevorgyan, V. PY - 2007 TI - Transition Metal Chemistry of Cyclopropenes and Cyclopropanes SP - 3117-79 KW - Cyclopropenes, transition metal catalysis AB - A review of transition metal-catalyzed chem. of three-membered carbocycles, e.g., cyclopropenes, methylenecyclopropanes and vinylcyclopropanes, and their reaction mechanisms. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Hashmi, A.S.K. PY - 2007 TI - Gold-Catalyzed Organic Reactions SP - 3180-211 KW - Gold catalysts AB - A review. This review covered all gold-catalyzed org. reactions published until Oct. 2006 in both homogeneous and heterogeneous catalysis. According to the reactivity patterns and functional groups in the substrates, reactions were classified into four major sections, including nucleophilic addn. to C-C multiple bonds, activation of carbonyl groups and alcs., carbon monoxide involved reaction, hydrogenation reaction and oxidn. and epoxidns. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Sawwan, N. AU - Greer, A. PY - 2007 TI - Rather Exotic Types of Cyclic Peroxides: Heteroatom Dioxiranes SP - 3247-85 KW - Dioxiranes, heteroatom Dioxiranes, tetrahedral Dioxiranes, trigonal bipyramidal AB - A review, including among heteroatom dioxiranes: tetrahedral dioxiranes, trigonal bipyramidal dioxiranes, and cyclic and ring-opened species. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Das, S. AU - Chandrasekhar, S. AU - Yadav, J.S. AU - Gree, R. PY - 2007 TI - Recent Developments in the Synthesis of Prostaglandins and Analogues SP - 3286-337 KW - Prostaglandins Prostacyclins Cyclopentenone prostaglandins AB - A review on the synthesis of cyclopentane prostaglandins, cyclopentenone prostaglandins and prostacyclin and derivs. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Gelalcha, F.G. PY - 2007 TI - Heterocyclic Hydroperoxides in Selective Oxidations SP - 3338-61 KW - Hydroperoxides, heterocyclic AB - A review. Included are N-, O-, N,S-, and N,Se-heterocyclic hydroperoxides. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Bifulco, G. AU - Dambruoso, P. AU - Gomez-Paloma, L. AU - Riccio, R. PY - 2007 TI - Determination of Relative Configuration in Organic Compounds by NMR Spectroscopy and Computational Methods SP - 3744-79 KW - NMR , natural products AB - This review is focused upon the state-of-the-art NMR methods currently in use for relative configurational assignment in org. compds., notably of complex natural products. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Marcus, Y. PY - 2007 TI - Gibbs Energies of Transfer of Anions from Water to Mixed Aqueous Organic Solvents SP - 3880-97 KW - Gibbs energies, solvent transfer AB - A review with 75 refs. JO - Chemical Reviews VL - 107 ER - TY - JOUR AU - Berova, N. AU - Di Bari, L. AU - Pescitelli, G. PY - 2007 TI - Application of Electronic Circular Dichroism in Configurational and Conformational Analysis of Organic Compounds SP - 914-31 KW - Electronic circular dichroism AB - This tutorial review is addressed to readers with a background in basic org. chem. and spectroscopy, but without a specific knowledge of electronic CD. It describes the fundamental principles, instrumentation, data anal., and different approaches for interpretation of ECD. The discussion focuses on the application of ECD, also in combination with other methods, in structural anal. of org. compds., including host-guest complexes, and will emphasize the importance of the interplay between configurational and conformational factors. The tutorial also covers modern supramol. aspects of ECD and recent developments in computational methods. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Perez-Garcia, L. AU - Amabilino, D.B. PY - 2007 TI - Spontaneous Resolution, Whence and Whither: From Enantiomorphic Solids to Chiral Liquid Crystals, Monolayers and Macro- and Supra-Molecular Polymers and Assemblies SP - 941-67 KW - Enantiophobic molecules Enantiophilic molecules Resolution, spontaneous AB - A review. One of the great challenges in stereochem. is the explanation of why some mols. resolve spontaneously while others do not. In this crit. review the recent advances in the creation of chiral systems from achiral and racemic compds. in three-, two- and one-dimensional systems are discussed. There are some groups of mols. in some systems that do tend to display conglomerates, which may suggest that there are enantiophobic and enantiophilic mols. whose assembly is guided by the structural and thermodn. properties of the systems in question. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Fairlamb, I.J.S. PY - 2007 TI - Regioselective (Site-selective) Functionalization of Unsaturated Halogenated Nitrogen, Oxygen and Sulfur Heterocycles by Pd-Catalyzed Cross-Couplings and Direct Arylation Processes SP - 1036-45 KW - Heterocycles, halogenated, functionalization AB - A review. This tutorial review focuses on several practical synthetic transformations utilizing palladium catalysis that facilitate the synthesis of functionalized unsatd. heterocycles in a regioselective (site-selective) manner. Cross-couplings of electron-deficient, electron-neutral, and electron-rich unsatd. halogenated heterocycles with various organometallic reagents, and other types of nucleophiles, are detailed. Direct arylation of electron-rich unsatd. heterocyclic compds. by C-H functionalization is also presented. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Schnuerch, M. AU - Spina, M. AU - Khan, A.F. AU - Mihovilovic, M.D. AU - Stanetty, P. PY - 2007 TI - Halogen Dance Reactions - A Review SP - 1046-57 KW - Halogen dance reactions AB - A review. Halogen Dance (HD) reactions are a useful tool for synthetic chemists as they enable access to positions in arom. and heteroarom. systems for subsequent functionalization which are often difficult to address by other methods, hence, allowing entry to versatile scaffolds. While the method can be extremely useful, this transformation is often neglected upon designing synthetic sequences. This may be largely attributed to the lack of comprehensive ref. works covering the general principles and outlining the versatility and limitations of the technique. The following review tries to present HD reactions in a clear and concise manner in order to convince more chemists of its advantages. It covers the field of HD reactions from their first observation in 1951 until the present. The important contributions leading to the elucidation of the mechanism are briefly outlined followed by a detailed mechanistic section and a discussion of factors which influence HD reactions. Finally, an overview of HD reactions on various carbocyclic and heterocyclic ring systems and its applications in the synthesis of complex compds. is given. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Campeau, L.-C. AU - Fagnou, K. PY - 2007 TI - Applications of and Alternatives to .p.-Electron-Deficient Azine Organometallics in Metal Catalyzed Cross-Coupling Reactions SP - 1058-68 KW - Azine organometallics, .p.-electron deficient Azine biaryls AB - A review. While the use of .p.-deficient azine halides in palladium catalyzed cross-coupling reactions is common, the use of .p.-electron deficient azine organometallics has been less intensively examd. In recent years, important advances have been made that are beginning to address this deficiency and need. The purpose of this tutorial review is to highlight and discuss the innovations that facilitate the synthesis of azine-contg. biaryls with a focus on the pyridine structural motif. Given JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Campos, K.R. PY - 2007 TI - Direct sp3 C-H Bond Activation Adjacent to Nitrogen in Heterocycles SP - 1069-84 KW - Heterocycles, nitrogen, functionalization AB - A review. Activation of sp3 C-H bonds adjacent to nitrogen in heterocycles is an attractive transformation that is emerging as a practical method in org. synthesis. This tutorial review aims to summarize the key examples of direct functionalization of nitrogen-contg. heterocycles via metal-mediated and metal-catalyzed processes, which is meant to serve as a foundation for future investigations into this rapidly developing area of research. The review covers functionalization of N-heterocycles via .a.-lithiation with alkyllithium/diamine complexes, .a.-amino radical formation, metal-catalyzed direct C-H activation, C-H oxidns. and oxidative couplings, and metal-catalyzed carbene insertions. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Heller, B. AU - Hapke, M. PY - 2007 TI - The Fascinating Construction of Pyridine Ring Systems by Transition Metal-Catalysed [2+2+2] Cycloaddition Reactions SP - 1085-94 KW - Pyridines, via [2+2+2] cycloaddition AB - A review (42 ref.). Cycloaddn. reactions compose one of the most important classes of reactions when it comes to the simultaneous formation of several bonds in one reaction step. The de novo construction of carbocyclic arom. systems from acetylenes was also found as an excellent possibility for the assembly of heteroarom. systems. The transition metal-catalyzed [2 + 2 + 2] cycloaddn. reaction constitutes a fascinating tool for the synthesis of pyridines from nitriles and the most recent developments demonstrate the ability to control the substitution pattern as well as the possibility of introducing chirality by the use of achiral substrates and a chiral catalyst under mild conditions.In this tutorial review we are focusing on the de novo construction of pyridine ring systems by the transition metal-catalyzed [2 + 2 + 2] cycloaddn. reaction. After surveying the mechanistic features and intermediates of the reaction depending on the different metal complexes used, he prepn. of achiral pyridine derivs is presented. The last section describes the advances in the synthesis of chiral pyridines and biaryls using the cyclotrimerisation method. The various possibilities of introducing chirality by catalytic means are presented and illustrated by instructive examples. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - D'Souza, D.M. AU - Mueller, T.J.J. PY - 2007 TI - Multi-Component Syntheses of Heterocycles by Transition-Metal Catalysis SP - 1095-108 KW - Heterocycles, via Pd, Rh, Ru, Cu Heterocycles, via multicomponent synthesis AB - A review. For a long time multi-component syntheses of heterocycles have undeniably been a domain of classical carbonyl condensation chem. However, the advent of transition-metal catalysis not only has fertilized strategies in heterocyclic synthesis by uni- and bimol. transformations but the past decade has also witnessed a rapid development of transition-metal catalysis in new multi-component reactions (MCR). Expectedly, palladium catalyzed processes have received a dominant position, yet, other transition-metal complexes are catching up implying organometallic elementary steps that reach even further than cross-coupling and carbometallation. Besides domino MCRs that are purely based upon organometallic catalysis the sequential and consecutive combination with condensation, addn. and cycloaddn. steps opens a vast playground for the invention of new sequences in heterocyclic synthesis. This tutorial review (55 ref.) outlines the underlying reaction based principles of transition-metal catalysis in multi-component syntheses of heterocycles, summarizes recent developments of palladium catalyzed MCR, and highlights the more recent contributions to MCR based heterocyclic synthesis by virtue of rhodium, ruthenium, and copper catalysis. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Davies, H.M.L. AU - Hedley, S.J. PY - 2007 TI - Intermolecular Reactions of Electron-Rich Heterocycles with Copper and Rhodium Carbenoids SP - 1109-19 KW - Pyrroles, with Cu/Rh carbenoids Furans, with Cu/Rh carbenoids Indoles, with Cu/Rh carbenoids Benzofurans, with Cu/Rh carbenoids AB - A review. This tutorial review describes the reactions of the electron-rich heterocycles pyrrole, furan, indole and benzofuran with copper and rhodium carbenoids. Two main reaction pathways are possible, involving either a concerted non-synchronous cyclopropanation or zwitterionic intermediates. A diverse range of products are possible and the outcome is very dependent on the structure of the heterocycle and the carbenoid. To emphasize this point the carbenoids are considered in terms of three classes: acceptor, acceptor-acceptor, and donor-acceptor carbenoids. Unusual catalytic asym. transformations can be achieved with this chem. while the asym. induction is strongly influenced by how the carbenoid can approach the heterocycles. This tutorial review gives an overview of the general features that govern the chem. of metal carbenoids with heterocycles and presents a mechanistic rationale for the range of products that can be formed. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Song, J.J. AU - Reeves, J.T. AU - Gallou, F. AU - Tan, Z. AU - Yee, N.K. AU - Senanayake, C.H. PY - 2007 TI - Organometallic Methods for the Synthesis and Functionalization of Azaindoles SP - 1120-32 KW - Axaindoles, synthesis Pyrrolopyridines, synthesis AB - A review. Azaindoles (also called pyrrolopyridines) constitute essential subunits in many pharmaceutically important compds. The synthesis of azaindoles has been a great synthetic challenge for chemists. Many classical methods for indole synthesis (such as Fischer and Madelung cyclizations) often cannot be effectively applied to the synthesis of the corresponding azaindoles. In recent years, advances in organometallic chem. have enabled a no. of novel and efficient methodologies for azaindole formation as well as for the further functionalization of azaindole templates. In this tutorial review, we have surveyed the recent development of organometallic chem.-based methods for azaindole synthesis. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Nishiyama, H. PY - 2007 TI - Synthesis and Use of Bisoxazolinyl-Phenyl Pincers SP - 1133-41 KW - Bisoxazolinyl-phenyl pincers Pincer ligands AB - A review. The bisoxazolinyl-Ph (Phebox) ligand is an example of an N,C,N tridentate (pincer type) ligand, which has a central C-metal covalent bond and two oxazolines. In this tutorial review, synthetic methods to prep. bisoxazolinyl-Ph derivs. and their transition-metal complexes including Rh, Ir, Pt, Pd, Ni and Cu, are summarized. Several applications to homogeneous and asym. catalysis with chiral bisoxazolinyl-Ph metal complexes were reviewed. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Minatti, A. AU - Muniz, K. PY - 2007 TI - Intramolecular Aminopalladation of Alkenes as a Key Step to Pyrrolidines and Related Heterocycles SP - 1142-52 KW - Aminopalladation, of alkenes Pyrrolidines, via aminopalladation of alkenes Palladium compounds, 2-amino alkyl- AB - This review describes the synthesis of 2-amino alkyl-palladium compds. and renders special attention on the subsequent manipulation of the alkyl-palladium group. That by carefully choosing the appropriate conditions, a wide variety of different heterocyclic structures are accessible which arise from reactions such as hydroamination, aza-Heck coupling, aminocarbonylation or oxidative processes such as aza-Wacker reaction and 1,2-difunctionalization is reviewed. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Chemler, S.R. AU - Fuller, P.H. PY - 2007 TI - Heterocycle Synthesis by Copper Facilitated Addition of Heteroatoms to Alkenes, Alkynes and Arenes SP - 1153-60 KW - Heterocycles, from alkenes, with Cu Heterocycles, from arenes, with Cu AB - A review. The de novo synthesis of small org. heterocyclic mols. has benefited from recent protocols for copper-facilitated addns. of heteroatoms to alkenes, alkynes and arenes. This tutorial review summarizes a no. of these recent contributions (63 ref.). Copper salts can facilitate bond formations due to their ability to serve as Lewis acids, oxidizing agents and transition metal catalysts. The current understanding of the mechanisms of these reactions is presented. This review should be of interest to chemists involved in the synthesis of heterocycles and those investigating transition metal facilitated reactions. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Schlosser, M. AU - Mongin, F. PY - 2007 TI - Pyridine Elaboration through Organometallic Intermediates: Regiochemical Control and Completeness SP - 1161-72 KW - Pyridine, hetero-, metalation Pyridine, hetero, substitution AB - A review (86 refs.). Pyridines carrying heterosubstituents (such as carboxy, amido, amino, alkoxy or trifluoromethyl groups or solely individual halogen atoms) can be readily and site selectively metalated. Subsequent reaction with a suitable electrophile opens rational access to a wealth of new building blocks for the synthesis of biol. active compds. This approach relies on organometallic methods, which are both efficacious and extremely flexible as far as the substitution site and the product structure are concerned. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Seregin, I.V. AU - Gevorgyan, V. PY - 2007 TI - Direct Transition Metal-Catalyzed Functionalization of Heteroaromatic Compounds SP - 1173-1193 KW - Heteroaromatics, functionalization AB - A review with 117 refs. summarizes the progress made during the last two decades in the development of catalytic reactions capable of activating unreactive C-H bonds. The methods discussed here allow for the synthesis JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Wilson, R.M. AU - Danishefsky, S.J. PY - 2007 TI - Applications of Total Synthesis Toward the Discovery of Clinically Useful Anticancer Agents SP - 1207-26 KW - Anticancer agents AB - A review discusses the work of the Danishefsky group in the total synthesis of natural products with antitumor activity and the use of natural product synthesis in the generation of analogs with improved antitumor activity. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Bennett, C.S. AU - Wong, C.-H. PY - 2007 TI - Chemoenzymatic Approaches to Glycoprotein Synthesis SP - 1227-38 KW - Glycoproteins, synthesis AB - A review. The construction of homogeneous glycoproteins presents a formidable challenge to the synthetic chemist. Over the past few years there has been an explosion in the no. of methods developed to address this problem. These methods include the development of novel ligation technologies for the synthesis of the protein backbone, as well chem. and enzymic approaches for introducing complex glycans into the peptide backbone. This tutorial review discusses the application of these techniques to the synthesis of peptides and proteins possessing well defined glycans. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Georgiev, I.G. AU - MacGillivray, L.R. PY - 2007 TI - Metal-Mediated Reactivity in the Organic Solid State: From Self-Assembled Complexes to Metal-Organic Frameworks SP - 1239-48 KW - Solid state organic reactions, with metals AB - A review. The purpose of this tutorial review is to address the use of metal ions to mediate reactions in the org. solid state. We describe metal complexes and coordination networks that facilitate dimerizations, oligomerizations and polymns. of olefins and acetylenes via irradn. (e.g. UV and 60Co ?-rays) and thermal annealing. We show how metal ions can be utilized to direct the formation of polymers and mols. We also describe how supramol. chem. has recently influenced dimerization processes in self-assembled metal-org. solids. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Moses, J.E. AU - Moorhouse, A.D. PY - 2007 TI - The Growing Applications of Click Chemistry SP - 1249-62 KW - Click chemistry AB - A review. Click chem. is a modular synthetic approach towards the assembly of new mol. entities. This powerful strategy relies mainly upon the construction of carbon-heteroatom bonds using "spring-loaded" reactants. Its growing no. of applications are found in nearly all areas of modern chem. from drug discovery to materials science. The copper(I)-catalyzed 1,2,3-triazole forming reaction between azides and terminal alkynes has become the gold std. of Click chem. due to its reliability, specificity and biocompatibility. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Gazit, E. PY - 2007 TI - Self-Assembled Peptide Nanostructures: The Design of Molecular Building Blocks and Their Technological Utilization SP - 1263-9 KW - Peptides, nanostructures AB - A review. The process and applications of peptide self-assembly into nanotubes, nanospheres, nanofibrils, nanotapes, and other ordered structures at the nano-scale are discussed in this tutorial review. The formation of well-ordered nanostructures by a process of self-assocn. represents the essence of modern nanotechnol. Such self-assembled structures can be formed by a variety of building blocks, both org. and inorg. Of the org. building blocks, peptides are among the most useful ones. Peptides possess the biocompatibility and chem. diversity that are found in proteins, yet they are much more stable and robust and can be readily synthesized on a large scale. Short peptides can spontaneously assoc. to form nanotubes, nanospheres, nanofibrils, nanotapes, and other ordered structures at the nano-scale. Peptides can also form macroscopic assemblies such as hydrogels with nano-scale order. The application of peptide building blocks in biosensors, tissue engineering, and the development of antibacterial agents has already been demonstrated. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Gomez, R. AU - Seoane, C. AU - Segura, J.L. PY - 2007 TI - The First Two Decades of a Versatile Electron Acceptor Building Block: 11,11,12,12-Tetracyano-9,10-Anthraquinodimethane (TCAQ) SP - 1305-22 KW - Tetracyanoanthraquinodimethane (TCAQ) AB - A review. This crit. review surveys the development of the structural and electrochem. knowledge of the TCAQ moiety since its discovery, nearly two decades ago, until the present. Addnl., recent advances in the chem. and functionalization of this versatile building block are highlighted, with special emphasis on the strategies devoted to the prepn. of donor-acceptor mol. and polymeric materials. The applications of TCAQ-based materials in materials science as elec. conductors, mol. rectifiers, in photoinduced electron transfer processes, optoelectronic devices and as electrochiroptical materials are also reviewed (89 refs.). JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Wang, C. AU - Xi, Z. PY - 2007 TI - Co-operative Effect of Lewis Acids with Transition Metals for Organic Synthesis SP - 1395-406 KW - Lewis acids combined with transition metals AB - A review. Transition metal-mediated or -catalyzed carbon-carbon bond or carbon-heteroatom bond forming reactions are among the most powerful tools in org. synthesis. In addn., Lewis acid-mediated or -catalyzed org. transformations are widely used. In this context, an effective combination of these two powerful protocols or an efficient cooperation of transition metals with Lewis acids should open a new era in synthetic chem. This tutorial review summarizes representative synthetic methodologies developed in the past decades employing this co-operative effect. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Severin, R. AU - Doye, S. PY - 2007 TI - The Catalytic Hydroamination of Alkynes SP - 1407-20 KW - Alkynes, hydroamination AB - The review focus on recent developments in intermol. hydroamination of alkynes and developments in catalysts that appeared in the literature between the end of 2002 and Oct. 31, 2006. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Fisk, J.S. AU - Mosey, R.A. AU - Tepe, J.J. PY - 2007 TI - The Diverse Chemistry of Oxazol-5-(4H)-ones SP - 1432-40 KW - Oxazolones AB - A review. The assembly of structurally diverse scaffolds via substrate controlled diversity oriented synthesis (DOS) proved to be an effective tool in the discovery of novel biol. important compds. This tutorial review aims to summarize some of the more recent applications of oxazolones as a general template for the stereoselective syntheses of amino acids and heterocyclic scaffolds. A brief introduction covers a short history, nomenclature and general reactivity of oxazolones. The main body of this tutorial review highlights several applications of oxazolones as starting blocks for the diverse and stereoselective synthesis of amino acids, oxazoles, .b.-lactams, pyrroles, imidazolines, pyrrolines, and imidazoles. JO - Chemical Society Reviews VL - 36 ER - TY - JOUR AU - Macias-Ruvalcaba, N.A. AU - Evans, D.H. PY - 2007 TI - Electron Transfer and Structural Change: Distinguishing Concerted and Two-Step Processes SP - 4386-95 KW - Electron-transfer, structural change reactions AB - A review. In electron-transfer reactions accompanied by structural changes, the structural change can be concerted with electron transfer or can occur in a sep. reaction either preceding or following the electron-transfer step. In this paper we discuss ways of distinguishing concerted reactions from the latter two-step type. Included are recent examples in which no intermediates have been detected in the reactions, thus precluding the direct assignment to the two-step category. In these cases, other means are used to build support for the two-step mechanism with respect to the concerted process. These include an example of structural change preceding electron transfer, a demonstration that the current models of concerted reactions cannot fit the voltammetric data, and a case in which an independent measure of the inner reorganization energy was used to show that the reaction could not be a concerted electron transfer and structural change. JO - Chemistry--A European Journal VL - 13 ER - TY - JOUR AU - Brik, A. AU - Wong, C.-H. PY - 2007 TI - Sugar-assisted Ligation for the Synthesis of Glycopeptides SP - 5670-5 KW - Glycopeptides, sugar-assisted ligation AB - A review. Chem. synthesis of glycoproteins from readily available materials is a powerful method for obtaining a pure product with full control of its at. structure. Sugar-assisted ligation (SAL) is an emerging approach that allows the synthesis of a large glycopeptide from two unprotected fragments. Contrary to other ligation methods that are limited to the use of a cysteine residue or depend on external auxiliary, SAL takes advantage of the existing sugars in glycopeptides to promote proximity between the two peptides to facilitate an amide bond formation. JO - Chemistry--A European Journal VL - 13 ER - TY - JOUR AU - Westerhausen, M. AU - Gaertner, M. AU - Fischer, R. AU - Langer, J. AU - Yu, L. AU - Reiher, M. PY - 2007 TI - Heavy Grignard Reagents: Challenges and Possibilities of Aryl Alkaline Earth Metal Compounds SP - 6292-306 KW - Grignard reagents, heavy alkaline earth AB - A review. Compds. of the type aryl-M-X, with M = Ca, Sr, Ba and X as any kind of ligand (such as halide, phosphanide, amide, aryl), are presented. The low reactivity of the heavy alk. earth metals calcium, strontium, and barium enforces an activation prior to use for the direct synthesis. The insertion of these metals into C-I bonds of aryl iodides (direct synthesis) yields aryl metal iodides and has to be performed at low temps. and in THF. Aryl alk.-earth-metal compds. show some characteristics: (1) the ease of ether cleavage enforces low reaction temps., (2) for Sr and Ba the Schlenk equil. is shifted towards homoleptic MI2 and MPh2, (3) high soly. of diaryl alk.- earth-metal derivs. in THF even at low temps. initiated quantum chem. investigations on the aggregation behavior, and (4) a strong low field shift of the 13C resonances of the ipso carbon atoms in NMR spectra was obsd. First results from quantum chem. calcns. on diaryl dicalcium(I) suggest a long Ca-Ca bond with a considerable Ca-Ca bond dissocn. energy. Initial results on a selection of applications such as metalation, metathesis, and addn. reactions of aryl calcium compds. are presented as well. JO - Chemistry--A European Journal VL - 13 ER - TY - JOUR AU - Yudin, A.K. AU - Hili, R. PY - 2007 TI - Overcoming the Demons of Protecting Groups with Amphoteric Molecules SP - 6538-42 KW - Protecting groups, amphoteric molecules AB - A review. Synthetic org. chemists have long depended on protecting group manipulations when faced with the challenges of chemoselectivity and functional group incompatibility. Overcoming this dependence will improve the overall efficiency of chem. synthesis. By taking advantage of orthogonally reactive functional groups, amphoteric mols. can afford access not only to more efficient and strategic syntheses but also to the development of novel chem. transformations. JO - Chemistry--A European Journal VL - 13 ER - TY - JOUR AU - Opsitnick, E. AU - Lee, D. PY - 2007 TI - Two-Dimensional Electronic Conjugation: Statics and Dynamics at Structural Domains Beyond Molecular Wires SP - 7040-9 KW - Molecular wires AB - A review. Chem. architectures supporting a high degree of electronic conjugation serve as important functional components in devices and materials for advanced electronic and photonic applications. Increasing the spatial dimensionality of such constructs can fundamentally modify their optoelectronic properties and significantly alter intra- and intermol. interactions that are crucial for understanding and controlling charge/energy-transfer processes. In this article, emerging design principles in the construction of well-defined conjugated platforms beyond mol. wires are highlighted. Both covalent and noncovalent approaches can be strategically employed to position one-dimensional (1D) substructures in a spatially well-defined manner in order to enhance both structural and functional complexity in a two-dimensional (2D) setting. A predictable and controllable switching mechanism can be designed and implemented with mobile 2D electronic conjugation that operates by correlated motions of inherently rigid ID subunits. This emerging "dynamic" approach complements and challenges the prevailing "static" paradigm of conjugated chem. architectures. JO - Chemistry--A European Journal VL - 13 ER - TY - JOUR AU - Paquette, L.A. PY - 2006 TI - Synthesis and Unprecedented Reactivity Characteristics of Unsaturated Bridgehead Sultams SP - 1-10 KW - Sultams, bridgehead, unsaturated AB - A review. JO - Chemtracts VL - 19 ER - TY - JOUR AU - Lang, S. PY - 2006 TI - Efficient Two-Pot Procedure for the Preparation of Anilines from Readily Available Aldehydes SP - 17-22 KW - Anilines, from aldehydes AB - A review with commentary on research by H. Neumann et al (2003). JO - Chemtracts VL - 19 ER - TY - JOUR AU - Kellogg, R.M. PY - 2006 TI - Multicomponent Reactions with Ketene Imine Intermediates Formed from the Reaction of Sulfonyl Azides with Acetylenes SP - 31-7 KW - Ketene imine intermediates Acetylenes, with sulfonyl azides AB - A review with commentary. JO - Chemtracts VL - 19 ER - TY - JOUR AU - Behera, M. PY - 2006 TI - Recent Asymmetric Synthesis of the Anti-Influenza Neuraminidase Inhibitor Oseltamivir (Tamiflu) SP - 38-44 KW - Tamiflu synthesis Oseltamivir synthesis Anti-influenza agents AB - A review. The title research of Y. Yeung, S. Hong, and Ej. Corey (2006) and M. Shibasaki et al. (2006) is reviewed with commentary and 5 refs. JO - Chemtracts VL - 19 ER - TY - JOUR AU - Sieck, S.R. AU - Hanson, P.R. PY - 2006 TI - Ring-Closing Metathesis of Sterically and Electronically Demanding Systems SP - 280-94 KW - Ring-closing metathesis, sterically hindered AB - A review. Ring-closing metathesis (RCM) has become a powerful tool in org. synthesis. Recently, the development of a no. of new, well-defined metathesis catalysts has expanded the scope of this transformation into areas of synthesis that were not previously possible. In this review, examples of RCM of sterically and electronically demanding systems are discussed. JO - Chemtracts VL - 19 ER - TY - JOUR AU - Anzenbacher, P. AU - Nishiyabu, R. AU - Palacios, M.A. PY - 2006 TI - N-Confused Calix[4]pyrroles SP - 2929-38 KW - Calixpyrroles, N-confused Pyrroles, N-confused calix[4]pyrroles AB - This is a first review devoted to N-confused calix[4]pyrroles (NCCPs). NCCPs are a relatively recent arrival to the family of the pyrrole-based anion binding macrocyclic compds. being for the first time identified in 1999. Yet, in a relatively short time these calix[4]pyrrole (CP) isomers attracted attention of the community of research groups interested in anion binding and sensing. This is because they are relatively easy to synthesize, but mainly because they posses anion-binding properties that are different from that of regular calix[4]pyrroles. The difference in anion-binding properties stems from a different binding mode between the NCCP and anion. While the regular CPs adopt in the complex an ideal cone-like conformation where all four pyrroles-NHs engage in hydrogen bonding to the anion, the inverted pyrroles do not allow forming the cone. NCCPs bind anions via a confused cone (CC), by three NH hydrogen bonds with an anion and a CH-anion contact. This different binding mode results also in different anion-binding affinity and selectivity compared to regular CPs. Also, the inverted pyrroles offer a unique possibility for selective chem. modification of the receptor. The corresponding colorimetric sensors were tested for anion binding applications. The results of colorimetric assays for anions are presented and potential applications discussed. A review. JO - Coordination Chemistry Reviews VL - 250 ER - TY - JOUR AU - Yamaguchi, Y. AU - Ding, W. AU - Sanderson, C.T. AU - Borden, M.L. AU - Morgan, M.J. AU - Kutal, C. PY - 2007 TI - Electronic Structure, Spectroscopy, and Photochemistry of Group 8 Metallocenes SP - 515-24 KW - Metallocenes AB - A review of spectral and photochem. studies of ferrocene, ruthenocene, and several of their benzoyl-substituted derivs. is presented which has provided valuable information about the electronic structures and excited state reactivities of these group 8 metallocenes. The presence of a benzoyl group on one or both cyclopentadienyl rings of the metallocene strongly influences the electronic transitions obsd. in the UV-visible spectral region. While the parent complexes display low-intensity, solvent-insensitive ligand field absorption bands, the monobenzoyl and 1,1'-dibenzoyl derivs. exhibit bands that are much more intense and sensitive to the soln. environment. This behavior results from the mixing of appreciable metal-to-ligand charge transfer (MLCT) character into the low-energy excited states of the benzoyl-substituted complexes. Resonance Raman data lend strong support to this MLCT assignment. Irradn. of a metallocene dissolved in Et 2-cyanoacrylate results in the anionic polymn. of the electrophilic monomer. Studies of the kinetics and mechanism of this photoinitiated polymn. process reveal that it occurs by two competing charge transfer-induced pathways, the relative importance of which depends upon the identity of the metal and the presence or absence of the benzoyl substituent. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Arnold, P.L. AU - Pearson, S. PY - 2007 TI - Abnormal N-Heterocyclic Carbenes SP - 596-609 KW - Carbenes, N-heterocyclic AB - A review of metal N-heterocyclic carbene (NHC) complexes, which are often more straightforward to make than the phosphine analogs with which they are often compared and are generally more stable, less odorous and on many occasions are anywhere between 100 and 1000 times more effective catalysts. For a decade it was assumed that NHCs always interacted with metal atoms in the same way. However, examples have now been found that exhibit unusual binding behavior. It is important to understand why such abnormal binding occurs and what effects this could have on the catalytic properties of NHC complexes. Display Omitted. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Pugh, D. AU - Danopoulos, A.A. PY - 2007 TI - Metal Complexes with 'Pincer'-type Ligands Incorporating N-Heterocyclic Carbene Functionalities SP - 610-41 KW - Carbenes, N-heterocyclic, pincer ligands AB - A review of the coordination and organometallic chem. of linear, rigid, tridentate ligands, which incorporate at least one N-heterocyclic carbene and other classical' donors, is presented and reviews across the periodic table with emphasis on unique features due to the presence of the N-heterocyclic carbene donor. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Lin, I.J.B. AU - Vasam, C.S. PY - 2007 TI - Preparation and Application of N-Heterocyclic Carbene Complexes of Ag(I) SP - 642-70 KW - Carbenes, N-heterocyclic, Ag complexes AB - A review of the current status (up to 31 July 2006) of Ag(I) N-heterocyclic carbene complexes is presented with various NHC systems ranging from five membered to seven membered rings, including imidazolium, benzimidazolium, imidazolinium, triazolium, pyrimidinium, pyrazolium, seven-membered amidinium, and naphthimidazolium moieties, etc. It is the authors' intention to provide an updated, and comprehensive review on the subject of Ag(I)-NHCs, which may further accelerate work on this topic. The main features of this review are to focus on (a) the ease and limitations in the synthesis of Ag(I)-NHCs, (b) the parameters influencing the solid state structures of Ag(I)-NHCs, and (c) the efficacy of Ag(I)-NHCs in transmetalation reactions. In particular, the authors would like to evaluate the widely adopted Ag2O technique in the prepn. of Ag(I)-NHCs and the subsequent NHC transfer reactions, to afford other metal-NHCs. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Colacino, E. AU - Martinez, J. AU - Lamaty, F. PY - 2007 TI - Preparation of NHC-Ruthenium Complexes and Their Catalytic Activity in Metathesis Reaction SP - 726-64 KW - Carbenes, N-heterocyclic, Ru complexes AB - A review on the synthesis of four-, five- and six-membered, satd. and unsatd. N-heterocyclic carbenes used in the prepn. of their corresponding Ru complexes (Grubbs' 2nd-generation, Fischer-type, Hoveyda-Grubbs, homo and hetero-bimetallic) is presented both in soln. and on solid support. The catalytic activity of the different complexes in Ru-catalyzed metathesis reaction is compared and explained by their structural features. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Esteruelas, M.A. AU - Lopez, A.M. AU - Olivan, M. PY - 2007 TI - Osmium-Carbon Double Bonds: Formation and Reactions SP - 795-840 KW - Osmium-carbon double bonds AB - A review reports on the chem. of the Os-C double bond, including alkylidene or carbene, vinylidene, and allenylidene derivs. Within the 1st type of compds., the authors show the synthetic methods and reactivity of half-sandwich derivs., including cyclopentadienyl and arene complexes, carbene compds. derived from alkynes, .a.,.b.-unsatd. carbene species, and osmacyclopropene, hydride-carbene, osmafurane, and osmapyrrole complexes. The vinylidene compds. include: half-sandwich, PCP pincer, hydride-vinylidene, azavinylidene-vinylidene, and metallaarene derivs. For their study the allenylidene complexes were divided into half-sandwich and nonhalf-sandwich compds. The transformation from hydride-carbyne to carbene is analyzed, the prepn. of butadienyl compds. via vinylidene intermediates is shown, and the assembly of org. mols. on allenylidene species to form osmacyclopentapyrrole derivs. is described. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Mata, J.A. AU - Poyatos, M. AU - Peris, E. PY - 2007 TI - Structural and Catalytic Properties of Chelating Bis- and Tris-N-Heterocyclic Carbenes SP - 841-59 KW - Carbenes, N-heterocyclic, chelating AB - A review of the use of polydentate NHC ligands which gave new compds. whose stability is entropically improved by the chelate effect. Chelate-N-heterocyclic ligands also provide interesting features that can allow fine tuning of topol. properties such as steric hindrance, bite angles, chirality and fluxional behavior. In this manuscript, attention to compds. with chelate-N-heterocyclic ligands in bidentate and tripod coordination forms is reported. Special attention is paid to structural and catalytic properties. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Diez-Gonzalez, S. AU - Nolan, S.P. PY - 2007 TI - Stereoelectronic Parameters Associated with N-Heterocyclic Carbene (NHC) Ligands: A Quest for Understanding SP - 874-83 KW - Carbenes, N-heterocyclic AB - A review of the latest advances in N-heterocyclic carbene-based organometallic chem. is given which has drawn increasing attention to this class of ancillary ligands as an attractive alternative to tertiary phosphines. Studies focusing on the fundamental steric and electronic factors characterizing this family of compds. are therefore essential for the rationalization of the activity obsd. for such organometallic complexes in metal-mediated org. transformations. This knowledge is also of fundamental importance in catalyst design efforts. This review intends to provide a comprehensive overview of the progress in this area. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Ellis, B.D. AU - Macdonald, C.L.B. PY - 2007 TI - Stable Compounds Containing Heavier Group 15 Elements in the +1 Oxidation State SP - 936-73 KW - Triphosphenium salts Phosphamethine cyanine dyes Phosphide anions Pnictaalkenes Phosphinidenes AB - A review. This review provides an oxidn. state model that emphasizes the similarities in the structural features, bonding and reactivities of mols. contg. main group elements in a particular oxidn. state. Using this model, the syntheses, structural features and selected aspects of the chem. of stable compds. contg. group 15 elements (pnictogens) in the +1 oxidn. state are examd. Mol. types that are considered include: Triphosphenium salts, phosphamethine cyanine dyes, phosphide anions, certain pnictaalkenes, certain phosphinidenes and their heavier analogs, among others. Theor. models are presented to rationalize the factors that render such mols. stable. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Herndon, J.W. PY - 2007 TI - The Chemistry of the Carbon-Transition Metal Double and Triple Bond: Annual Survey Covering the Year 2005 SP - 1158-258 KW - Carbon-transition metal double bond AB - A review of papers published in the year 2005 that focus on the synthesis, reactivity, or properties of compds. contg. a C-transition metal double or triple bond. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Sivaramakrishna, A. AU - Clayton, H.S. AU - Kaschula, C. AU - Moss, J.R. PY - 2007 TI - Transition Metal-Alkenyl Complexes [M-(CH2)nCH=CH2, N > Or = 2]: Synthesis, Structure, Reactivity and Applications SP - 1294-308 KW - Metal-alkenyl complexes Ethylene ologomerization Metallacycloalkenes, via ring closing metathesis AB - A review and historical perspective is followed by an overview of methods used to synthesize transition metal-alkenyl complexes LmM(CH2)n-CH=CH2 (Lm = other ligands, M = transition metal and n ? 2). Both mono- and bis(alkenyl) compds. are discussed. X-ray structures show that the alkenyl groups can coordinate either in an .h.1- or an .h.1,.h.2-fashion. Reactivity patterns for these metal-alkenyl complexes can be different to those shown by metal-alkyl complexes and these differences are highlighted. For example bis(alkenyl) complexes can undergo ring closing metathesis (RCM) reactions to give metallacycloalkenes, as demonstrated recently by the authors' research group. The intermediacy of transition metal-alkenyl species in ethylene oligomerization and other catalytic reactions is also discussed. JO - Coordination Chemistry Reviews VL - 251 ER - TY - JOUR AU - Szilagyi, L. AU - Varela, O. PY - 2006 TI - Non-Conventional Glycosidic Linkages: Syntheses and Structures of Thiooligosaccharides and Carbohydrates with Three-Bond Glycosidic Connections SP - 1745-70 KW - Glycosides, thio Thiooligosaccharides AB - This review presents the construction of the interglycosidic linkage, in which the oxygen atom is replaced by sulfur, usually involves one of the following reactions: nucleophilic displacement of good leaving groups in a carbohydrate moiety by a sugar thiol; Michael and Michael-type addns. of sugar thiols to unsatd. acceptors; ring-opening of aziridines and oxiranes by thiosugars; enzyme-catalyzed couplings of thiosugar moieties. The application of these reactions for the syntheses of thiooligosaccharides are surveyed, and the biol. activities of the resulting products briefly described. Carbohydrate structures incorporating three-bond glycosidic linkages with two heteroatoms are uncommon in Nature. The -N-O- interglycosidic bond in the oligosaccharide part of enediyne antibiotics is partly responsible for their potent antitumor activities. The disulfide bond which plays an essential role in proteins has recently been introduced as an interglycosidic connecting motif. The sulfenamide functionality is the sulfur analog of the hydroxylamine type glycosidic linkages in calicheamicins. Novel glycosylation strategies have recently been developed by taking advantage of unconventional, three-bond glycosidic linkages to construct neoglycoproteins and other glycoconjugates which are increasingly important tools in glycobiol. and drug discovery. To explore conformational preferences and mol. flexibility in these structures NMR spectroscopy, chiroptical methods and X-ray crystallog. are being used, supplemented by mol. modeling calcns. The structural features will be briefly discussed with relevance to biol. interactions such as enzyme binding. JO - Current Organic Chemistry VL - 10 ER - TY - JOUR AU - Drabowicz, J. AU - Kudelska, W. AU - Lopusinski, A. AU - Zajac, A. PY - 2007 TI - The Chemistry of Phosphinic and Phosphinous Acid Derivatives Containing t-Butyl Group as a Single Bulky Substituent: Synthetic, Mechanistic and Stereochemical Aspects SP - 3-15 KW - Phosphines, t-butyl Butylphenylthiophosphinic acid, tertiary AB - A review of basic synthetic procedures commonly applied for the prepn. of racemic and optically active phosphinic and phosphinous acid derivs. contg. a t-Bu group as a single bulky substituent are presented. Mechanistic and stereochem. aspects of the presented protocols are discussed. Structural studies, which include the x-ray and vibrational CD-based detns. of the abs. configuration at the stereogenic P atom and calcns. of conformational equil. for a few model compds. are also mentioned. The use of the optically active t-butylphenylthiophosphinic acid as a chiral solvating agent is illustrated. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Sasaki, S. AU - Yoshifuji, M. PY - 2007 TI - Synthesis, Structure and Properties of Crowded Triarylphosphines SP - 17-31 KW - Triarylphosphines AB - A review of crowded triarylphosphines which have attracted broad interest for a long time since they have unique structure, properties, and reactivity is presented. This review article focuses on synthesis, structure, properties, and application of crowded triarylphosphines represented by trimesitylphosphine and tris(2,4,6- triisopropylphenyl)phosphine, which are of interest from contemporary viewpoint of material science rather than ligands for transition metal catalysis. Synthesis of the crowded triarylphosphines by reaction of various aryl organometallic reagents with P halides, structures of the crowded triarylphosphines in solid and soln., redox properties and structure-property relation, cation radicals of crowded triarylphosphines, and construction of the functional mols. carrying crowded triarylphosphines are described. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Bansal, R.K. AU - Gupta, N. AU - Kumawat, S.K. PY - 2007 TI - Recent Advances in the Chemistry of Anellated Azaphospholes SP - 33-47 KW - Azaphospholes, anellated AB - A review covers the synthesis, structural characterization, reactions and theor. calcns. of azaphospholes anellated to a six- or five-membered heterocyclic ring, reported during the last 10-12 years. Azaphospholes are 6.p. arom. heterocycles incorporating at least one .s.2,?3-P atom and one .s.3,?3-N atom. Three synthetic methods, [4+1] cyclocondensation, [3+2] cyclocondensation and 1,5-electrocyclization make a variety of these P heterocycles available. The arom. character of these compds. was confirmed by carrying out .d. functional theory (DFT) calcns. Mainly 1H, 13C and 31P NMR studies were employed for the structural characterization. Almost all the functionalities present in the azaphosphole ring were studied and electrophilic substitution reactions of the 1-unsubstituted compds. and JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Zablocka, M. AU - Majoral, J.-P. PY - 2007 TI - Synthesis of Phosphorus Ligands from Zirconium Reagents. A Useful Approach SP - 49-60 KW - Zirconium reagents, P ligands Zirconocenes, phosphorus ligands Phosphorus ligands Phosphozirconocenes AB - A review of the use of Zr reagents as the Schwartz reagent [Cp2ZrHCl]n, the dimethylzirconocene Cp2ZrMe2, the zirconocene [Cp2Zr], and the diphenylzirconocene Cp2ZrPh2 in the synthesis of new linear and cyclic P-C and P-N ligands. 1,1 Diphosphines can be prepd. from unsatd. monophosphines. A useful methodol. involving ring opening reactions permits the prepn. of phosphinite-phosphine and bis-phosphinite ligands. N-functionalized imines and .b.-diimines substituted with phosphino groups were obtained from cyanophosphines or dinitriles. Carbozirconation of chlorophospha-imine leads to the unprecedented P-metalated iminophosphorane which presents a versatile reactivity towards electrophiles and small unsatd. mols. Constraint three and four P cycles can be easily isolated using [Cp2M] (M = Zr or Ti). Interactions between benzynezirconocene and unsatd. phosphines afford numerous methods to prep. linear and cyclic P reagents. Enantiomerically pure iminophosphines can be synthesized from phosphinozirconocene complexes. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Holz, J. AU - Gensow, M.N. AU - Zayas, O. AU - Boerner, A. PY - 2007 TI - Synthesis of Chiral Heterocyclic Phosphines for Application in Asymmetric Catalysis SP - 61-106 KW - Phosphines, chiral heterocyclic Phosphiranes Phosphetanes Phospholes Phosphinanes AB - A review of the synthesis of chiral heterocyclic phosphines, such as phosphiranes, phosphetanes, phospholes and phosphinanes is presented. These compds. play a pivotal role as ligands and organocatalysts, resp., in asym. reactions. Synthetic approaches will be analyzed in the framework of several sub-categories e.g. the prepn. of mono-, bis- and poly(phosphines). General synthetic strategies for the prepn. of large families of related compds. is considered such as 1. stereoselective .a.-alkylation of phosphine oxides or phosphine boranes, 2. ring closure by substitution reactions and 3. hydrogenations of unsatd. P-heterocylic compds., followed by epimerization reactions. Besides these general methodologies also protocols leading to a single phosphine is discussed. In some cases also the prepn. of such phosphines will be presented, which have not yet been used in asym. catalysis, however, which have - owing to their structure - some relevance to synthetic methodologies or compds. discussed herein. For most phosphines presented applications in asym. catalytic reactions will be briefly mentioned together with characteristic enantioselectivities achieved. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Keglevich, G. AU - Baan, Z. AU - Hermecz, I. AU - Novak, T. AU - Odinets, I.L. PY - 2007 TI - The Phosphorus Aspects of Green Chemistry: The Use of Quaternary Phosphonium Salts and 1,3-Dialkylimidazolium Hexafluorophosphates in Organic Synthesis SP - 107-26 KW - Green chemistry, phosphorus Ionic liquids AB - A review summarizes and critically discusses the data accumulated in recent years on the synthesis and use of P contg. ionic liqs., such as imidazolium hexafluorophosphates and phosphonium salts. The search for suitable ionic liqs. that are nonvolatile, nontoxic, dissolve a variety of reactants and are recyclable is a real challenge for chemists to be able to replace the traditional solvents that are volatile, flammable and toxic. As regards the prepn. of ionic liqs., the key steps are quaternization and the introduction of the corresponding anion. Phys. properties of the ionic liqs. can be fine-tuned by selecting suitable cation-anion pairs. The reactions studied in ionic liqs. embraces catalytic hydrogenations, transfer hydrogenations, oxidns., hydroformylations, carbonylations, alkylations, acylations, nucleophilic substitutions, halogenations, condensations, Diels-Alder reactions, Michael addns., coupling reactions and transformations in organophosphorus chem. Ionic liqs. are esp. suitable to accommodate catalytic reactions where one of the components is a gas. Stress was laid to highlight the chemo-, regio-, diastereo- and, esp., the enantioselectivity of the reactions performed in ionic liqs. The data on the ecotoxicity of imidazolium hexafluorophosphates and phosphonium salts are briefly discussed. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Ferreira, V.F. PY - 2007 TI - Synthesis of Heterocyclic Compounds by Carbenoid Transfer Reactions SP - 177-93 KW - Heterocycles, via carbenoid transfer Carbenoids, from diazocarbonyls Pyrroles, from diazocarbonyls Aziridines, from diazocarbonyls Dihydrofurans, from diazocarbonyls AB - A review. Over the last 30 years, the use of diazocarbonyl compds. has been a very fertile field for the development of new synthetic methods for constructing C-C bonds and heterocyclic rings. The reactions of the carbenoids derived from the diazocarbonyls offer exciting new strategies for the construction of complex target mols. due to the range of unusual transformations and cascade sequences which can be utilized. This review provides an update of the significant advances in the field since the year 2000 in the synthesis of several heterocycles (pyrrole, aziridines, dihydrofurans, etc.) by inter- and intramol. insertions of carbenoid species, generated from a-diazo-ß-keto compds., into carbon-hydrogen or heteroatom-hydrogen bonds. New methodologies and unusual synthetic transformations will be highlighted. Although heterocycles have very important uses, the focus of this survey will be directed not to their use but to the methods of prepn. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Musilek, K. AU - Kuca, K. AU - Jun, D. AU - Dolezal, M. PY - 2007 TI - Progress in Synthesis of New Acetylcholinesterase Reactivators During the Period 1990-2004 SP - 229-38 KW - Acetylcholinesterase reactivators AB - A review of synthesis of reactivators of acetylcholinesterase is presented which are very important components in the treatment of intoxications caused by organophosphate inhibitors such as tabun, sarin, soman, VX etc. and insecticides like echothiofat, metrifonat, chlorpyrifos etc. These inhibitors covalently bind on active site of mentioned enzyme and irreversibly inhibit its activity. The reactivator breaks the inhibitor-enzyme covalent bond and restores its activity. Unfortunately, there is no reactivator applicable for every type of inhibition; it means that every structural changes in the mol. of inhibitor needs a specific structure of the reactivator. Therefore, development of more active acetylcholinesterase reactivators with broader spectrum is a major challenge actual from the point of view of war operations, accidents or terroristic attacks. Synthetic approaches, biol. activity evaluation and structure-activity relation studies of newly prepd. acetylcholinesterase reactivators from 1990 to 2004 are summarized. Synthetic procedures used and the evaluation of antidotal efficacies are mentioned for individual types of reactivators. The main attention was paid to reactivators derived from pyridine carbaldoxime and imidazole carbaldoxime. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Wang, X. AU - Liang, M. AU - Zhang, J. AU - Wang, Y. PY - 2007 TI - Selective Hydrogenation of Aromatic Chloronitro Compounds SP - 299-314 KW - Aromatics, chloronitro Chloronitroanilines, from chloronitrobenzene AB - A review. Many effective strategies have been developed in order to inhibit the hydrodechlorination in the selective hydrogenation of chloronitrobenzenes to chloroanilines which are important intermediates in the chem. and industry of dyes, herbicides, pesticides and medicines. However, hydrogenolysis of the carbon-halogen bond as a defect of the hydrogenation process could not be avoided completely over the metal catalysts reported previously, esp. at complete conversion of the substrates. Recently this problem was overcome by the invention of nanocomposite catalysts composed of noble metal nanoclusters and inorg. semiconductor nanoparticles. Over these nanocomposite catalysts, the hydrodechlorination of o-chloroaniline was completely suppressed even at 100% conversion of ortho-chloronitrobenzene. This review decribes the great efforts and remarkable contributions of different authors during the long exploration for the solns. of this hard obstacle. Stress is placed on supported metal catalysts and polymer-protected metal nanoclusters or colloid catalysts. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Toth, G.K. AU - Kele, Z. AU - Varadi, G. PY - 2007 TI - Phosphopeptides - Chemical Synthesis, Analysis, Outlook and Limitations SP - 409-26 KW - Phosphopeptides Protein phosphorylation AB - A review. Protein phosphorylation is one of the most important post-translational events in cell regulation and signal transduction. Since the isolation of phosphorylated peptides from biol. sources is usually not feasible, there is a need for efficient chem. phosphorylation methods to allow the study of the role of phosphorylation/dephosphorylatio n in biol. processes. The recent developments in phosphopeptide chem. (special protecting groups for the phosphate moiety and new amidite reagents) have provided peptide chemists with a wide variety of different strategies applicable for work with the sensitive phosphoserine-, phosphothreonine- and phosphotyrosine-contg. peptides. This has made possible the efficient chem. prepn. of longer, multiply phosphorylated, possibly cell-permeable or fluorescent residue-bearing peptides. A review. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Feske, B.D. PY - 2007 TI - Bestatin: Three Decades of Synthetic Strategies SP - 483-96 KW - Bestatin, synthesis AB - A review. Bestatin [i.e, ubenimex; N-[(2S,3R)-3-amino-2-hydroxy-1-oxo-4- phenylbutyl]-L-leucine] is a dipeptide that can treat a variety of diseases. Over the last thirty years synthetic chemists have developed an assortment of routes to optically pure (-)-bestatin. Many strategies include the use of pure starting materials like sugars and amino acids. In addn., the utilization of chiral auxiliary groups have been implemented to achieve an increase in stereoselectivity and to simplify the purifn. process. Lastly, asym. catalysis using enzymes or inorg. catalysts has also been used to afford the desired stereochem. This review will cover 23 synthetic strategies to (-)-bestatin through the year 2005. A review. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Perdih, A. AU - Dolenc, M.S. PY - 2007 TI - Recent Advances in the Synthesis of Unnatural .a.-Amino Acids SP - 801-32 KW - Amino acids, .a., unnatural AB - A review. The synthesis of unnatural .a.-amino acids is an area of research that has gained a lot of attention in recent years. The availability of synthetic methods for novel unnatural .a.-amino acid derivs. and related compds. will be a crit. point in the de novo design of mols. that mimic the conformation of the natural, active peptides. These mols. (peptidomimetics) are designed to display high receptor affinity and selectivity, in addn. to enhanced bioavailability and metabolic stability. This review focuses on selected recent synthetic methodologies leading to unnatural .a.-amino acids including chiral catalysts that enable enantioselective synthesis and microwave-assisted synthesis. Solid phase synthesis and construction of organometallic .a.-amino acids reveal the scope of influence that this field has in org. chem. Addnl., the article is aimed to provide a brief insight into the biosynthetic approaches to the synthesis of .a.-amino acid derivs., and to give the reader an appreciation of the field. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Madkour, H.M.F. AU - Elgazwy, A.S.H. PY - 2007 TI - Utilities of Some Carbon Nucleophiles in Heterocyclic Synthesis SP - 853-908 KW - Heterocycles, carbon nucleophiles AB - A review. New developments in the utilities of some carbon nucleophiles in heterocyclic synthesis are reviewed. General synthetic routes based on the utilization of carbon nucleophiles of active methylene are discussed. The major methods and modifications are analyzed. Heterocycles are ubiquitous in all kinds of compds. of interest, and among all the possible synthetic methods of achieving their introduction into a structure, probably the use of carbon nucleophile analogs is the most direct one. The present review deals with the generation and the synthetic applications of carbon nucleophiles, which are used as scaffolds for heterocyclic synthesis, and can be considered as an updated review. Therefore the only refs. published upon the second quarter of 2003 are included, and the same restrictions to the literature coverage apply. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Pastor, I.M. AU - Yus, M. PY - 2007 TI - The Prins Reaction: Advances and Applications SP - 925-57 KW - Prins reaction Alkene-aldehyde condensation AB - A review. The acid-catalyzed alkene-aldehyde condensation, known as the Prins reaction, is reviewed. Lewis acids, org. acids and supported catalysts have been reported to assist both the Prins acyclic reaction and the Prins cyclization. Acetals and oxocarbenium ions (generated from aldehydes and alcs.) have been described as reacting systems in the Prins reaction. Prins cyclizations have been used to form mainly five- and six-membered rings, albeit formation of seven-, eight-, and nine-membered rings have been described. The Prins reaction (and cyclization) has been developed as a key strategic element in the total synthesis of different natural products. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Chaturvedi, D. AU - Ray, S. PY - 2007 TI - Versatile Use of Carbon Dioxide in Synthesis of Organic Carbamates SP - 987-98 KW - Carbamates, via carbon dioxide AB - A review on versatile use of carbon dioxide in synthesis of org. carbamates. Org. carbamates classically have been synthesized starting from amines using harmful and toxic reagents like phosgene or its derivs. and carbon monoxide. Recently carbon dioxide was used as a cheap and harmless reagent for the synthesis of org. carbamates in the gaseous or supercrit. state or in an electrochem. process as an alternative to the harmful and toxic reagents. The present review will deal with the extensive use of carbon dioxide in the synthesis of org. carbamates. JO - Current Organic Chemistry VL - 11 ER - TY - JOUR AU - Murphy, P.V. AU - Dunne, J.L. PY - 2006 TI - Syntheses of Peptidomimetics Based on Pyranose and Poly-Hydroxylated Piperidine Scaffolds SP - 403-37 KW - Peptidomimetics, pyranose Peptidomimetics, piperidine AB - A review with refs. There has been significant progress in application of pyranoses and related compds. towards drug discovery and development. This review focuses on strategies for grafting of pharmacophore groups at selected positions on pyranoside and related imino-sugar scaffolds. Recent developments in the solid phase synthesis of prospecting combinatorial libraries, syntheses of pyranose based sugar amino acids and other scaffolding for peptidomimetics are included. Although no drug mol. has been developed a no. of novel potent ligands for receptors have been identified. It has been shown that these pyranoside derivs. could have improved cellular permeability over peptides. Progress in this area is continually dependent on advances in synthetic carbohydrate chem. both in soln. and on solid phase. These include the development of orthogonal protecting group strategies, strategies for regioselective manipulation of pyranoside hydroxyl groups and strategies that could take increasing advantage of chemoselective reactions. In addn. a greater understanding of structural carbohydrate chem. and the preferred orientations of groups attached to pyranose scaffolds may facilitate synthesis of more potent ligands for receptors. JO - Current Organic Synthesis VL - 3 ER - TY - JOUR AU - Koketsu, M. AU - Ishihara, H. PY - 2007 TI - Synthesis and Applications of Chalcogenoamide: Thio-, Seleno- and Telluroamides SP - 15-29 KW - Thioamides, heterocycle synthesis Selenoamides, heterocycle synthesis Telluroamides, heterocycle synthesis AB - A review. This provides a comprehensive survey of the recent progress in the various synthetic methods of the chalcogenoamides (thioamide, selenoamide and telluroamide), their application in the prepn. of heterocycles and their biol. significances. JO - Current Organic Synthesis VL - 4 ER - TY - JOUR AU - Honaker, M.T. AU - Hovland, J.M. AU - Salvatore, R.N. PY - 2007 TI - The Synthesis of Tertiary and Secondary Phosphines and Their Applications in Organic Synthesis SP - 31-45 KW - Phosphines, tertiary Phosphines, secondary AB - A review. This review focuses on a literature survey of the uses and the different approaches for the syntheses of tertiary and secondary phosphines. Their applications in org. synthesis are briefly overviewed along with basic methods for their prepn. and phys. properties are also discussed. Where possible, the relative advantages of ditertiary and disecondary phosphines in important org. reactions are often industrially important org. reactions that are also compared. JO - Current Organic Synthesis VL - 4 ER - TY - JOUR AU - Zappia, G. AU - Gacs-Baitz, E. AU - Delle Monache, G. AU - Misiti, D. AU - Nevola, L. AU - Botta, B. PY - 2007 TI - Oxazolidin-2-one Ring, A Popular Framework in Synthetic Organic Chemistry: Part 1. The Construction of the Oxazolidin-2-One Ring SP - 81-135 KW - Oxazolidin-2-one ring AB - A review. The 1,3-oxazolidin-2-one nucleus is a popular heterocycle framework in synthetic org. chem., as well as in medicinal chem. This review deals with the huge no. of synthetic approaches addressed to the construction of this five-member ring, with a particular care for the mechanistic and stereochem. outcome. JO - Current Organic Synthesis VL - 4 ER - TY - JOUR AU - Hua, R. AU - Jiang, J.-L. PY - 2007 TI - Recent Development of Rhenium-Catalyzed Organic Synthesis SP - 151-74 KW - Rhenium complexes, catalysts AB - A review. Most of rhenium complexes are stable with different oxidn. states and moisture-, air-tolerant, these remarkable properties result in the diverse applications of them in catalytic org. synthesis as homogeneous catalysts. The purpose of this review is to summarize the recent development of rhenium-catalyzed org. synthesis focusing on the formation of carbon-carbon, carbon-heteroatom (C-Si, C-N, C-O, C-S) bonds, functionalization of carbon-hydrogen bond, oxidn. and redn. reaction, oxygen and sulfur transfer, photoredn. of carbon dioxide, as well as polymn., etc. JO - Current Organic Synthesis VL - 4 ER - TY - JOUR AU - Patil, S. AU - Patil, R. PY - 2007 TI - Synthesis and Functionalization of Indoles Through Rhodium-Catalyzed Reactions SP - 201-22 KW - Indoles, via Rh catalysts AB - A review. Indoles are abundant in nature, and exhibit important biol. properties such as anti-inflammatory, antihypertensive, dopaminergic, antineoplastic, anticonvulsant, analgesic, sedative, muscle relaxant, and antimicrobial activities. Synthesis, and functionalization of pharmacol. active indoles continue to receive considerable attention in the field of synthetic org. chem. Recent advances toward synthesis of natural, and unnatural indoles were accelerated by transition metal catalysts, and in the context rhodium was proven an extremely useful metal due to its ability to catalyze an array of synthetic transformations with quite often-unique selectivity. This review describes the formation of indoles via rhodium catalyzed C-H, and X-H insertion (X = N, O, and S), cycloaddn., hydroformylation, bimetallic, and asym. hydrogenation reactions. Use of solid phase chem. in rhodium catalyzed indole synthesis was also discussed in the article. JO - Current Organic Synthesis VL - 4 ER - TY - JOUR AU - Chaturvedi, D. AU - Mishra, N. AU - Mishra, V. PY - 2007 TI - Various Approaches for the Synthesis of Organic Carbamates SP - 308-20 KW - Carbamates, organic, using carbon dioxide AB - A review. Org. carbamates classically were synthesized using harmful reagents like phosgene, its derivs. and CO. Recently, CO2 was used as a cheap and harmless reagent as an alternative to harmful reagents for the synthesis of org. carbamates in gaseous, supercrit. and electrochem. forms. The present review will deal the synthesis of org. carbamates from various starting materials from beginning to recent ones. JO - Current Organic Synthesis VL - 4 ER - TY - JOUR AU - Demir, A.S. AU - Emrullahoglu, M. PY - 2007 TI - Manganese(III) Acetate: A Versatile Reagent in Organic Chemistry SP - 321-51 KW - Manganese acetate AB - A review. Free radical reactions have become increasingly important, as well as a very attractive tool, in org. synthesis within the last two decades, due to their powerful, selective, specific, and mild reaction abilities. Mn(OAc)3 mediated oxidative free radical reactions were extensively developed in the last twenty years. Numerous regio-, chemo-, and stereoselective synthetic methods were developed in both inter- and intramol. reactions, and have detailed the progress of Mn(OAc)3 mediated oxidative free radical reactions since the end of the 19th century. The new literature about the new synthetic methods on Mn(OAc)3 mediated C-C bond formation and C-O bond formation reactions was not extensively reviewed. The present paper summarizes the recent developments in oxidative free radical reactions mediated by Mn(OAc)3. Mn(OAc)3 mediated reactions of conjugated systems (e.g., alkenes, alkynes, 1,3-alkadienes, 1,3-alkadiynes, 1-alken-3-ynes) with ß-dicarbonyl compds., Mn(OAc)3 mediated alkylation, such as the oxidative addn. of an aldehyde or ketone to alkenes, Mn(OAc)3 mediated free-radical cyclization of alkenes with active methylene compds. in the presence of O to afford the cyclic peroxides; lactone synthesis by the Mn(OAc)3 mediated oxidative addn. of carboxylic acids to alkenes, Mn(OAc)3 mediated cyclization of a-(methylthio)acetamides, enamides, and ß-keto carboxamides to afford cyclic products. Mn(OAc)3 oxidative free-radical cyclizations of allylic ß-dicarbonyl compds., for example, the cyclization of allylic ß-ketoesters to afford the corresponding ?-lactone. The reaction of alkenes with Na azide in the presence of HOAc was studied to afford 1.2-diazides. The selective oxidn. of enones led to a'-acetoxy-enones by Mn(OAc)3 oxidn. In general, Mn(OAc)3 oxidns. were characterized by higher a'-regioselectivity and chem. yields, and milder reaction conditions, in turn tolerating many sensitive functional groups. The use of Mn(OAc)3 in combination with other carboxylic acids or Mn(II) carboxylates extends this methodol. to the prepn. of a variety of a'-acyloxyenones that are otherwise inaccessible in a 1-step procedure. JO - Current Organic Synthesis VL - 4 ER - TY - JOUR AU - Bartoli, G. AU - Locatelli, M. AU - Melchiorre, P. AU - Sambri, L. PY - 2007 TI - Taking up the Cudgels for Perchlorates: Uses and Applications in Organic Reactions Under Mild Conditions SP - 2037-49 KW - Perchlorates AB - A review. Metal perchlorates are compds. of great chem. interest since they possess some unique properties, such as high electronegativity and relatively low charge .d., poor complexing ability, high soly. in various org. solvents and kinetic stability under mild conditions. Besides providing polar media when dissolved in solvents, metal perchlorates have recently found wide employment as Lewis acid promoters in various org. transformations, both in the development of new techniques for known and widely used reactions and in promotion of new kinds of reactivity. This paper presents a general overview of the more recent uses of Li, Mg, Zn and Ni perchlorates, underlining the fact that such perchlorates are quite safe chem. products under mild conditions. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Langer, P. PY - 2007 TI - Synthesis of Bridged and Nonbridged N-Heterocycles by Cyclocondensation of Bis(Silyl Enol Ethers) with Iminium Salts SP - 2233-8 KW - Iminium salts, cyclization, with bis(silyl enol ethers) Heterocycles, N-, bridged Benzobicyclononanones Tropinones, synthesis AB - A review. Cyclization reactions of iminium salts with bis(silyl enol ethers) - such as 1,3-bis(silyloxy)-1,3-butadienes and 1,1-bis(silyloxy)ketene acetals - allow a convenient synthesis of various bridged and nonbridged N-heterocycles. The iminium salts were generated in situ from pyridines, quinolines, isoquinolines, quinoxalines, pyrazines, quinazolines, and 2,5-dimethoxypyrrolidines. The products include 4-oxa-9-aza-7,7-benzobicyclo[3.3.1]nonan-3-ones, 7-oxa-1,4-diaza-2,3-benzobicyclo[4.3.0]non-2-en-6-ones, 7-oxa-1,4-diazabicyclo[4.3.0]non-2-en-6-ones, 3-hydroxy-9-aza-7,8- benzobicyclo[3.3.1]non-3-enes, 4-hydroxy-1,9-diaza-7,8- benzobicyclo[3.3.1]non-4-enes, alkylidene-7-oxa-1,4-diaza-2,3- benzobicyclo[4.3.0]non-2-enes, and tropinones. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Kirschning, A. AU - Kujat, C. AU - Luiken, S. AU - Schaumann, E. PY - 2007 TI - Small and Versatile - Formyl Anion and Dianion Equivalents SP - 2387-400 KW - Formyl anions AB - A review. This account provides a short overview of the synthetically important class of formyl anions and the less studied formyl dianion equiv. A brief literature survey, which particularly focuses on asym. homologation strategies, is complemented by a detailed description of lithiated (dimethoxymethyl)diphenylphosphane oxide, which is an ideal formyl anion equiv. in reactions with aldehydes. Under acidic conditions the intermediate ketene O,O-acetals afford homologated carboxylic esters whereas asym. dihydroxylation of ketene acetals leads to collapse of the intermediate diols furnishing the corresponding .a.-hydroxy carboxylic esters with high stereocontrol. Addnl., it is demonstrated that the silyl-substituted carbanion may be looked upon as a latent dianion that can react either with two electrophiles or with bis-electrophiles, the latter transformation yielding ring-closure coproducts. It is advantageous if the electrophiles are epoxides or epoxides carrying a remote leaving group. The carbanion will ring-open the epoxide and allow a C ? O silyl shift, thus generating the new carbanion. This then reacts with the second electrophile, either inter- or intramolecularly. The versatility of these two formyl anion equiv. is demonstrated by selected examples from natural product synthesis. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Palomo, C. AU - Oiarbide, M. AU - Laso, A. PY - 2007 TI - Recent Advances in the Catalytic Asymmetric Nitroaldol (Henry) Reaction SP - 2561-74 KW - Nitoaldol reaction, enantioselective Henry reaction, enantioselective AB - A review. Catalyst-controlled enantioselective nitroaldol (or Henry) reactions are presented. These reactions represent powerful C-C bond-forming tools and the resulting nitro alc. (nitroaldol) products can be transformed into a no. of nitrogen- and oxygen-contg. derivs. (nitroalkenes, amino alcs., amino acids, etc.). In addn. to substrate-controlled nitroaldol reactions (not covered), catalytic systems that provide good stereoselectivity have been developed in recent years. Through the use of preformed silyl nitronates as activated substrates, catalytic systems involving metallic Lewis acids or tetraalkylammonium salts have been deployed in fluoride-mediated nitroaldol reactions. In a further advance, catalytic systems capable of promoting direct nitroaldol reactions between unmodified nitroalkanes and aldehydes (ketones) with high yields and stereoselectivities have been developed. To this end, ambifunctional systems based on La, Zn, Cu, Co and Mg metal species are described, together with some organocatalysts. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - de Figueiredo, R.M. AU - Christmann, M. PY - 2007 TI - Organocatalytic Synthesis of Drugs and Bioactive Natural Products SP - 2575-600 KW - Natural product synthesis, organocatalytic AB - A review. Catalytic reactions are a key element in the design of sustainable chem. processes. As witnessed in the field of transition metal-catalyzed processes, only those reactions that are reliable over a broad substrate range and tolerant toward a multitude of functional groups have found their way into the repertoire of preparative chemists. Natural product synthesis provides a good benchmark for the maturity of a new synthetic method and in this microreview we discuss the scope and limitations of organocatalytic reactions in the synthesis of biol. important mols. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Li, G. AU - Saibau Kotti, S.R.S. AU - Timmons, C. PY - 2007 TI - Recent Development of Regio- and Stereoselective Aminohalogenation Reaction of Alkenes SP - 2745-58 KW - Alkenes, aminohalogenation AB - A review. This microreview presents the development of the catalytic aminohalogenation of olefins (49 ref.). The olefin substrates include electron-deficient and functionalized ones, such as .a.,.b.-unsatd. esters, .a.,.b.-unsatd. ketones and .a.,.b.-unsatd. nitriles. In addn., the first asym. aminohalogenation by the use of Evans chiral auxiliaries is also discussed. The convincing evidence is provided to support the aziridinium mechanism of aminohalogenation reaction. The applications of this reaction are described by converting vicinal haloamines into other important synthetic building blocks. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Shi, Y.-L. AU - Shi, M. PY - 2007 TI - Aza-Baylis-Hillman Reactions and Their Synthetic Applications SP - 2905-16 KW - Aza-Baylis-Hillman reaction AB - A review. Aza-Baylis-Hillman reaction has attracted much attention over the past decade. The origins and progress of aza-Baylis-Hillman reactions, including the development of catalysts and substrate scopes, mechanistic study, asym. reactions, and further transformations of the products are discussed. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Muzart, J. PY - 2007 TI - Procedures For and Possible Mechanisms of Pd-Catalyzed Allylations of Primary and Secondary Amines with Allylic Alcohols SP - 3077-89 KW - Amines, allylation Amines, with allylic alcohols AB - A review. This review describes the different Pd-catalyzed methods that afford allylic amines from intermol. reactions between allylic alcs. and amines and, with personal comments, the mechanisms that have been proposed. Allylic amines are an important class of compds., while a wide structural variety of allylic alcs. are com. available and are abundant in nature. The advantages of the use of allylic alcs. over that of their derivs. such as allylic esters or carbonates are the high atom efficiency and the formation only of water as the byproduct. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Beletskaya, I.P. AU - Ananikov, V.P. PY - 2007 TI - Unusual Influence of the Structures of Transition Metal Complexes on Catalytic C-S and C-Se Bond Formation Under Homogeneous and Heterogeneous Conditions SP - 3431-44 KW - Hydrothiolation Hydroselenation Bisthiolation Bisselenation Vinyl sulfides Vinyl selenides Alkynes, thiol addition Alkynes, selenol addition AB - A review. In the presence of transition metal catalysts, hydrothiolation and hydroselenation reactions, as well as bisthiolation and bisselenation reactions, were successfully carried with high selectivities and yields. New transition metal-catalyzed synthetic methods were developed for the prepn. of vinyl sulfides and vinyl selenides of various types. Mechanistic study revealed that a homogeneous catalytic system based on phosphine complexes of palladium is the best choice for carrying out stereoselective addns. of disulfides and diselenides to alkynes. A heterogeneous Ni-catalyzed reaction with a unique self-organized nanostructured catalyst was superior for carrying out regioselective addns. of thiols and selenols to alkynes. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Zanoni, G. AU - Pontiroli, A. AU - Marchetti, A. AU - Vidari, G. PY - 2007 TI - Stereoselective Carbonyl Allylation by Umpolung of Allylpalladium(II) Complexes SP - 3599-611 KW - Carbonyl allylation, allylpalladium Allylpalladium, umpolung reactions AB - A review. The nucleophilic palladium-mediated allylation of a carbonyl group requires the inversion of the reactivity (umpolung) of the .h.3-allylpalladium moiety. If the reaction is performed with a metal more electropos. than palladium, the stereochem. outcome is influenced by the solvent and by the reagent used for the umpolung. The stereoselectivity is also detd. by the rate of .h.3-.h.1-.h.3 equilibration of the .h.3-allylpalladium system relative to that of the transmetalation and addn. to the aldehyde. When the umpolung is carried out with .h.1- or bis(allylpalladium) complexes, the stereoselectivity mainly depends on the nature of the substituents on the allyl fragment. Asym. addn. has been achieved by using chiral ligands that promote palladium-mediated reactions with "hard" nucleophiles. Utilization of selected chiral monophosphanes/phosphoramidite as ligands induces enantioselectivity that depends on the nature of the aldehyde as well as of the umpolung agent. Modest enantiomeric excesses have been obtained by using preformed bis(allylpalladium) systems with one chiral allylic fragment. JO - European Journal of Organic Chemistry ER - TY - JOUR AU - Tverdokhlebov, A.V. PY - 2007 TI - Pyrrolo[2,1-b]thiazoles SP - 761-98 KW - Pyrrolothiazoles AB - A review. Synthesis and chem. properties of pyrrolo[2,1-b]thiazoles have been reviewed. The literature from 1940 to 2005 was covered (136 refs.). Utility of the title compds. as dyes and in photog., as well as their biol. activity were also discussed. JO - Heterocycles VL - 71 ER - TY - JOUR AU - Majhi, T.P. AU - Achari, B. AU - Chattopadhyay, P. PY - 2007 TI - Advances in the Synthesis and Biological Perspectives of Benzannulated Medium Ring Heterocycles SP - 1011-52 KW - Heterocycles, benzannulated AB - A review. Benzannulated medium ring heterocycles represent a class of compds., capable of binding to multiple receptors with high affinity and act as good antagonist. Exploration of these types of compds. in drug discovery is a rapidly emerging area in synthetic chem. and exploitation of these mols. will help researchers to discover biol. active compds. with a broad range of medicinal values. JO - Heterocycles VL - 71 ER - TY - JOUR AU - Jain, V.K. AU - Mandalia, H.C. PY - 2007 TI - The Chemistry of Calixpyrroles SP - 1261-314 KW - Calixpyrroles AB - This comprehensive review summarizes the progress made in chem. of calixpyrroles (meso-octasubstituted porphyrinogens) in terms of their synthesis, structure, conformation, functionalization and applications in various fields. Synthetic approaches towards calixpyrrole macrocycle core including one-pot condensation, [2 + 2] condensation and [3 + 1] condensation, and subsequent functionalization of the macrocycle formed at the .b.-position (C-rim), at the meso (bridge) position and at N-rim are discussed. The applications of functionalized calixpyrroles as optical or electrochem. sensors, as HPLC supports, or as anion-transporting agents are also reviewed. Synthesis of higher order calixpyrroles is briefly discussed. JO - Heterocycles VL - 71 ER - TY - JOUR AU - Sliwa, W. AU - Peszke, J. PY - 2007 TI - Inclusion Complexes Containing Quaternary Azaaromatic Moieties SP - 1685-713 KW - Cyclodextrins, inclusion complexes Cucurbiturils, inclusion complexes Calixarenes, inclusion complexes Azaaromatics, quaternary, inclusion complexes AB - A review. In the paper inclusion complexes of cyclodextrins, cucurbiturils and calixarenes contg. quaternary azaarom. moieties are described, followed by complexes of crown ethers, tweezers and clips. JO - Heterocycles VL - 71 ER - TY - JOUR AU - Itsikson, N.A. AU - Geide, I.V. AU - Morzherin, Y.Y. AU - Matern, A.I. AU - Chupakhin, O.N. PY - 2007 TI - Heteroditopic Receptors SP - 53-77 KW - Receptors, heteroditopic AB - The review outlines the recent advances in the field of coordination chem., and is focusing on the function-oriented design of heterotopic co-receptors. Comparative anal. of receptor ability for various classes of org. compds. toward two different substrates, ion pairs or zwitterionic species is presented. JO - Heterocycles VL - 2007 ER - TY - JOUR AU - Omae, I. PY - 2007 TI - Three Types of Reactions with Intramolecular Five-Membered Ring Compounds in Organic Synthesis SP - 2608-32 KW - Five-membered rings AB - A review. There are three types of reactions with intramol. five-membered ring compds. in org. syntheses: The first type is reactions involving intramol. five-membered ring compds. which are utilized for the ease of synthesis of these compds. and the stability of the products. The second is reactions performed via intramol. five-membered ring intermediates, because such intermediates are very reactive and labile compds. The third is the metal-catalyzed reactions with the intramol. five-membered ring compds. because these metal compds. have catalytic activities. The third type reactions involving intramol. five-membered ring pincer compds. are also provided. The first type reactions include carbonylations, alkenylations, alkynylations, acylations, isocyanations, Diels-Alder reactions, etc. The second type reactions include carbonylations, cross-coupling reactions, hydroacylations, ring expansion reactions, carbocyclizations, etc. The third type reactions include cross-coupling reactions, rearrangements, metatheses, redns., Michael reactions, dehydrogenations, Diels-Alder reactions, etc. JO - Journal of Organometallic Chemistry VL - 692 ER - TY - JOUR AU - Klingebiel, U. AU - Matthes, C. PY - 2007 TI - From Lithium Halosilylamide to Small and Large Ring Compounds, Iminosilenes and Iminosilanes SP - 2633-41 KW - Iminosilenes Iminosilanes Lithiumhalosilylamides AB - A review. Structure investigations on lithiumhalosilylamides have repeatedly yielded astonishing results. Depending on the solvents and the substitution of the nitrogen, they are isolated as acyclic, three- to penta-, bi-, and spiro-cyclic compds. The shortest Si-N bond (157.9 pm) of four-coordinated silicon is found in these salts. The different formation of silicon-nitrogen contg. rings by elimination of alk. halides from halosilylamides depends on the solvent and structural make-up of the halosilylamides. Four- to 14-membered rings are formed. Four-membered SiN-rings with the smallest angles at the silicon (76°), and the cyclodisilazane dications are obtained. Stable iminosilenes and iminosilanes are isolated and unusual cycloaddn. products are presented. JO - Journal of Organometallic Chemistry VL - 692 ER - TY - JOUR AU - Chivers, T. AU - Konu, J. AU - Ritch, J.S. AU - Copsey, M.C. AU - Eisler, D.J. AU - Tuononen, H.M. PY - 2007 TI - New Tellurium-Containing Ring Systems SP - 2658-68 KW - Tellurium ligands AB - A review. The recent discovery of a suitable synthesis of the monoanionic ditelluroimidodiphosphinate ligands [TePR2NPR2Te]- (R = Ph, iPr, tBu) has facilitated investigations of the fundamental chem. of these chelating inorg. ligands. This article is focused on aspects of that chem. in which the behavior of this ditelluro PNP ligand differs from that of the well-studied dithio and diseleno congeners. The emphasis is on new tellurium-contg. ring systems formed in: (a) redox transformations and (b) the synthesis of metal complexes. JO - Journal of Organometallic Chemistry VL - 692 ER - TY - JOUR AU - Balcells, D. AU - Maseras, F. PY - 2007 TI - Computational Approaches to Asymmetric Synthesis SP - 333-43 KW - Computational chemistry, asymmetric synthesis AB - A review. Theor. chem. has been successfully used as a powerful tool to obtain valuable insight into the mechanism and the origin of enantioselectivity in several asym. reactions of high interest. In this Perspective article, the application of QM, MM and QM/MM methods to the rationalization of electronic and steric effects upon enantioselectivity is briefly reviewed, considering some representative contributions of the last three decades. JO - New Journal of Chemistry VL - 31 ER - TY - JOUR AU - Mancin, F. AU - Tecilla, P. PY - 2007 TI - Zinc(II) Complexes as Hydrolytic Catalysts of Phosphate Diester Cleavage: From Model Substrates to Nucleic Acids SP - 800-17 KW - Phosphate diester bond cleavage AB - A review. The development of synthetic agents able to hydrolytically cleave phosphate diester bonds with high efficiency is a fascinating challenge, which will ultimately open the way to artificial nucleases able to compete with the natural enzymes. This Perspective highlights the progress reported in the realization of hydrolytic catalysts based on the Zn2+ ion, a metal ion which, due to its peculiar properties, is a very promising candidate. The review critically examines the reactivity of such catalysts toward model substrates and nucleic acids, paying particular attention to the strategies that can be pursued to improve efficiency and sequence selectivity. JO - New Journal of Chemistry VL - 31 ER - TY - JOUR AU - Hahn, U. AU - Cardinali, F. AU - Nierengarten, J.-F. PY - 2007 TI - Supramolecular Chemistry for the Self-assembly of Fullerene-Rich Dendrimers SP - 1128-38 KW - Fullerene dendrimers AB - A review discusses the generation of fullerene-rich dendrimers by self-assembly in which the branches of the dendrimers rather than their cores are substituted with fullerene moieties. JO - New Journal of Chemistry VL - 31 ER - TY - JOUR AU - Andres, R. AU - De Jesus, E. AU - Flores, J.C. PY - 2007 TI - Catalysts Based on Palladium Dendrimers SP - 1161-91 KW - Dendrimers, Pd AB - A review. This report reviews the role of palladium dendrimers in catalysis as (a) sol. macromols. for the support of catalysts, that are separable by nanofiltration techniques; (b) ligand-modifiers that can create specific metal nanoenvironments and tune the soly. of the catalyst; (c) spacers for the support of mol. catalysts that can proportionate a more homogeneous-like environment to the supported catalytic sites; and (d) precursors for the synthesis of mono- and bimetallic nanoparticles of controlled size and narrow size distribution. Some examples of catalysis with related metal systems, such as star-shaped mols. or hyperbranched polymers, are also given. JO - New Journal of Chemistry VL - 31 ER - TY - JOUR AU - Paryzek, Z. AU - Skiera, I. PY - 2007 TI - Synthesis and Cleavage of Lactones and Thiolactones. Applications in Organic Synthesis. A Review SP - 203-96 KW - Lactones Thiolactones AB - A review covering the synthesis of lactones including cyclizations, redns. and oxidns. and of lactone cleavage using hydrolysis with nucleophiles, redns. and reactions with organometallics. JO - Organic Preparations and Procedures International VL - 39 ER - TY - JOUR AU - Gallou, I. PY - 2007 TI - Unsymmetrical Ureas. Synthetic Methodologies and Application in Drug Design SP - 355-83 KW - Ureas, unsymmetric AB - A review on synthetic methodologies for unsym. ureas and their application in drug design. JO - Organic Preparations and Procedures International VL - 39 ER - TY - JOUR AU - Pace, A. AU - Buscemi, S. AU - Vivona, N. PY - 2006 TI - The Synthesis of Fluorinated Heteroaromatic Compounds. Part 2. Five-Membered Rings with Two Heteroatoms. A Review SP - 1-70 KW - Heteroaromatics, fluoro, 5-membered rings AB - A review. JO - Organic Preparations and Procedures International VL - Volume Date 2007, 39 ER - TY - JOUR AU - Balazs, G. AU - Gregoriades, L.J. AU - Scheer, M. PY - 2007 TI - Triple Bonds between Transition Metals and the Heavier Elements of Groups 14 and 15 SP - 3058-75 KW - Transition metals, triple bonds AB - A review. In the mid-1990s, the 1st examples of complexes contg. triple bonds between transition metals and heavier analogs of the C as well as the N groups are reported, thus signaling the beginning of a new era in organometallic chem. Since then the progress in this field was tremendous, with a large no. of representative complexes being isolated and characterized. This review highlights the astonishing development of the chem. of complexes contg. triple bonds between transition metals and the heavier elements of groups 14 and 15 since its birth. The synthesis and the structural and spectroscopic features of these compds. are comprehensively discussed. Furthermore, the elucidation of their bonding modes by quantum-chem. methods as well as the relation between the reactivities of these complexes and their electronic structures are presented. JO - Organometallics VL - 26 ER - TY - JOUR AU - Power, P.P. PY - 2007 TI - Bonding and Reactivity of Heavier Group 14 Element Alkyne Analogues SP - 4362-72 KW - Alkyne analogs, group 14 Digermynes Distannynes AB - A review. In this short review recent developments in the synthesis and spectroscopic characterization, as well as the bonding and reactivity, of heavier group 14 element alkyne analogs (REER, R = large aryl or silyl group; E = Si-Pb) are summarized. Stable examples of such compds. have been known only since 2000, although their bonding has been studied by theor. methods since the early 1980s. The use of very large substituents has enabled their isolation and the study of their reactions at room temp. All the currently known compds. possess trans-bent planar core structures and nonbonded electron d. at the tetrel (group 14 element). The bending increases with increasing at. no., and when E = Pb the triple bonding seen in the lighter carbon homolog has been transformed into a single bond and two nonbonded electron pairs. To a crude approxn. the bond order decreases by ca. 0.5 of a unit between elements upon descending the group. Currently available reactivity data show that the silicon and germanium derivs. are significantly more reactive than their tin or lead analogs. A "digermyne" has been shown to react directly with hydrogen under ambient conditions, suggesting the presence of some singlet diradical character. The "distannynes" have been shown to adopt either a multiply bonded structure similar to its germanium analog or a singly bonded structure like the lead species. Much further work will be required to obtain a clearer picture of this exciting new class of mols. JO - Organometallics VL - 26 ER - TY - JOUR AU - Gleiter, R. AU - Bleiholder, C. AU - Rominger, F. PY - 2007 TI - .a.-Metallocenylmethylium Ions and Isoelectronic Fulvene Complexes of d6 to d9 Metals. Structural Considerations SP - 4850-9 KW - Metallocenylmethylium ions AB - A review. This review collects the structural features of those metallocene derivs. in which a carbenium ion center is connected adjacent to a cyclopentadienyl ring .h.-bound to a transition metal. In the 1st part the authors briefly summarize the studies and observations that led to the structure of the .a.-ferrocenylmethylium ion. This part is followed by examples of metallocenylmethylium ions and metallocenyldimethylium dications of the Fe triad, the isoelectronic ferrocenylboranes, fulvenechromium tricarbonyl complexes, .a.-cymantrenylcarbenium ions, and [cyclopentadienyl- cyclobutadienecobalt] methylium ions. In all cases the authors notice a bending of the .a.-carbenium ion center toward the metal. The bending angle is largest for fulvenechromium tricarbonyl and the ruthenocenyl- and osmocenylmethylium ions. JO - Organometallics VL - 26 ER - TY - JOUR AU - Moss, R.A. AU - Tian, J. AU - Chu, G. AU - Sauers, R.R. AU - Krogh-Jespersen, K. PY - 2007 TI - New Mechanisms Centered on Reactive Intermediates: Examples from Diazirine and Carbene Chemistry SP - 993-1001 KW - Carbenes, intermediates Diazirinone Dichlorodiazirine Dichlorocarbenes AB - A review. Laser flash photolysis (LFP) of appropriate diazirine precursors afforded the UV spectra of methylchlorocarbene, benzylchlorocarbene, cyclopropylchlorocarbene, and 1- adamantylchlorocarbene. The .s. ? p transitions of these carbenes were used to directly monitor their reaction kinetics. The unusual and highly reactive N2CO compd., diazirinone, was obtained from the reaction of fluoride ion with p-nitrophenoxychlorodiazirine. Diazirinone fragmented to CO and N2 in a reaction that was exothermic by >90 kcal/mol. Dichlorodiazirine (DCD) was generated by the reaction of chloride ion with p-nitrophenoxychlorodiazirine. Reactions of dichlorocarbene generated from DCD are discussed. JO - Pure and Applied Chemistry VL - 79 ER - TY - JOUR AU - Beletskaya, I.P. AU - Ananikov, V.P. PY - 2007 TI - Addition Reactions of E-E and E-H Bonds to Triple Bond of Alkynes Catalyzed by Pd, Pt, and Ni Complexes (E = S, Se) SP - 1041-56 KW - Disulfide bonds, alkyne addition Diselenide bonds, alkyne addition Alkynes, reaction with sulfur AB - A review. The synthetic application and mechanistic aspects of transition-metal (Ni, Pd, Pt) catalyzed addn. of E-E and E-H (E = S, Se) bonds to alkynes were investigated in detail. This study revealed major factors controlling the selectivity of such addn. reactions. A new Ni-based catalytic system with a self-organized nanostructured catalyst has been designed to perform chem. transformation in high yield, under mild conditions. JO - Pure and Applied Chemistry VL - 79 ER - TY - JOUR AU - Chmielewski, M.J. AU - Zielinski, T. AU - Jurczak, J. PY - 2007 TI - Synthesis, Structure, and Complexing Properties of Macrocyclic Receptors for Anions SP - 1087-96 KW - Receptors, macrocyclic, for anions Isophthalamide macrocyclic receptors Dipicolinic macrocyclic receptors AB - A review. This account discusses the studies carried out in the authors' group on the structure-affinity relationships for macrocyclic anion receptors. This issue (namely, the macrocyclic effect, the influence of intramol. hydrogen bonds, and the correlation between the ring size and anion affinity) was investigated for amide-based macrocyclic receptors derived from isophthalic and dipicolinic diacids. It was found that, in contrast to acyclic diamides, macrocyclic isophthalamide receptors bind anions more weakly than their dipicolinic analogs; the phenomenon is explained by intramol. hydrogen bonds present in isophthalamide receptors. This obstacle can be overcome by the prepn. of a hybrid macrocycle based on both building blocks. JO - Pure and Applied Chemistry VL - 79 ER - TY - JOUR AU - Paz, F.A.A. AU - Klinowski, J. PY - 2007 TI - Designing Novel Organic-Inorganic Frameworks SP - 1097-110 KW - Coordination frameworks AB - A review. Crystal engineering of coordination frameworks is a topical and rapidly advancing field, and a variety of entirely new solid materials have been synthesized. We describe the main challenges involved in the hydrothermal approach to these materials using, as an example, cadmium- and zinc-based coordination frameworks. We discuss the unusual crystal architectures of the products, and show that the kind and quality of the resulting crystals are directly controlled by the compn. of the ternary reactive mixt. and the temp. regime used in the hydrothermal synthesis. JO - Pure and Applied Chemistry VL - 79 ER - TY - JOUR AU - Garcia-Rio, L. AU - Leis, J.R. AU - Mejuto, J.C. AU - Perez-Lorenzo, M. PY - 2007 TI - Microemulsions as Microreactors in Physical Organic Chemistry SP - 1111-23 KW - Microemulsions AB - A review. Microemulsions are very versatile reaction media which nowadays find many applications, ranging from nanoparticle templating to preparative org. chem. The thermodynamically stable and microheterogeneous nature of microemulsions, used as reaction media, induces drastic changes in the reagent concns., and this can be specifically used for tuning the reaction rates. In particular, amphiphilic org. mols. can accumulate and orient at the oil-water interface, inducing regiospecificity in org. reactions. In this review, we will show the recent tendencies of the use of microemulsions as org. reaction media. JO - Pure and Applied Chemistry VL - 79 ER - TY - JOUR AU - Kost, D. AU - Gostevskii, B. AU - Kalikhman, I. PY - 2007 TI - Silicon Rehybridization and Molecular Rearrangements in Hypercoordinate Silicon Dichelates SP - 1125-34 KW - Silicon dichelates AB - A review of research presented in 18th international conference on phys. org. chem. Hydrazide-based hypercoordinate silicon dichelates are remarkably flexible in terms of geometry and reactivity: this paper demonstrates how rather subtle constitutional changes result in dramatic geometrical and reactivity changes. A change of ligand-donor group from NMe2 to N:CMe2 changes the solid-state geometry from bicapped tetrahedral to octahedral. These two geometries are shown to coexist in soln. in dynamic equil. Hexacoordinate complexes are shown to dissoc. to pentacoordinate compds. in two distinct ways: ionic or neutral, depending on substitution. Hexacoordinate dichelates with imino-donor groups undergo a skeletal rearrangement (intramol. aldol-type condensation of imines), catalyzed by their dissocd. halide counterions. However, even in the absence of counterions, silacyclobutane dichelates undergo a similar rearrangement. JO - Pure and Applied Chemistry VL - 79 ER - TY - JOUR AU - El Seoud, O.A. PY - 2007 TI - Solvation in Pure and Mixed Solvents: Some Recent Developments SP - 1135-51 KW - Solvatochromism AB - A review. The effect of solvents on the spectra, absorption, or emission of substances is called solvatochromism; it is due to solute/solvent nonspecific and specific interactions, including dipole/dipole, dipole-induced/dipole, dispersion interactions, and hydrogen bonding. Thermo-solvatochromism refers to the effect of temp. on solvatochromism. The mol. structure of certain substances, polarity probes, make them particularly sensitive to these interactions; their solns. in different solvents have distinct and vivid colors. The study of both phenomena sheds light on the relative importance of the solvation mechanisms. This account focuses on recent developments in solvation in pure and binary solvent mixts. The former has been quant. analyzed in terms of a multiparameter equation, modified to include the lipophilicity of the solvent. Solvation in binary solvent mixts. is complex because of the phenomenon of "preferential solvation" of the probe by one component of the mixt. A recently introduced solvent exchange model allows calcn. of the compn. of the probe solvation shell, relative to that of bulk medium. This model is based on the presence of the org. solvent (S), water (W), and a 1:1 hydrogen-bonded species (S-W). Solvation by the latter is more efficient than by its precursor solvents, due to probe/solvent hydrogen-bonding and hydrophobic interactions. Dimethylsulfoxide (DMSO) is an exception, because the strong DMSO/W interactions probably deactivate the latter species toward solvation. The relevance of the results obtained to kinetics of reactions is briefly discussed by addressing temp.-induced desolvation of the species involved (reactants and activated complexes) and the complex dependence of kinetic data (obsd. rate consts. and activation parameters) in binary solvent mixts. on medium compn. JO - Pure and Applied Chemistry VL - 79 ER - TY - JOUR AU - Konstantinova, L.S. AU - Amelichev, S.A. AU - Rakitin, O.A. PY - 2007 TI - 1,2,3,4,5-Pentathiepins and 1,2,3,4,5-Pentathiepanes SP - 195-211 KW - Pentathiepanes AB - A review. Data on the synthesis and properties of seven-membered heterocyclic compds. contg. five successive S atoms and a C-C bond, 1,2,3,4,5-pentathiepins and -pentathiepanes, are generalized and described systematically. The bibliog. includes 104 refs. JO - Russian Chemical Reviews VL - 76 ER - TY - JOUR AU - Samsoniya, S.A. AU - Trapaidze, M.V. PY - 2007 TI - The Chemistry of Indoloindoles SP - 313-26 KW - Indoloindoles AB - A review of methods for the synthesis of substituted and unsubstituted indoloindoles. Characteristic features of electrophilic substitution in the indoloindole system and some transformations in the side chains are discussed. The bibliog. includes 86 refs. JO - Russian Chemical Reviews VL - 76 ER - TY - JOUR AU - Nifantyev, E.E. AU - Slitikov, P.V. AU - Rasadkina, E.N. PY - 2007 TI - Synthesis of Arylenephosphamacrocycles Using Tri- and Pentavalent Phosphorus Compounds SP - 327-38 KW - Arylenephosphamacrocycles Phenols, cyclophosphorylation AB - A review. Key results of research into the reactions of cyclophosphorylation of dibasic phenols and related compds. with tri- and pentavalent P compds. are analyzed. Structural features and chem. modification of macrocyclic systems obtained are considered. The bibliog. includes 63 refs. JO - Russian Chemical Reviews VL - 76 ER - TY - JOUR AU - Bagryansky, V.A. AU - Borovkov, V.I. AU - Molin, Y.N. PY - 2007 TI - Quantum Beats in Radical Pairs SP - 493-506 KW - Radicals, short-lived, in liquid solutions AB - A review. Possible fields of application of the phenomenon of quantum beats in spin-correlated radical pairs in studies of the properties of short-lived radicals (lifetimes of up to a few nanoseconds) in liq. solns. are considered. The theor. approaches to the description of this phenomenon and modern exptl. data are analyzed. JO - Russian Chemical Reviews VL - 76 ER - TY - JOUR AU - Koshino, M. AU - Tanaka, T. AU - Solin, N. AU - Suenaga, K. AU - Isobe, H. AU - Nakamura, E. PY - 2007 TI - Imaging of Single Organic Molecules in Motion SP - 853 KW - Transmission electron microscopy, hydrocarbon chain AB - Single small org. mol. either at rest or translating within a single-wall carbon nanotube (SWCNT) were obsd., with near-at. resoln., by transmission electron microscopy (TEM). The authors chose for this proof-of-principle study mols., contg. hydrocarbon chains covalently attached to an o-carborane end group, which serves as a tag for identification by its characteristic shape. Comparison of the exptl. images with simulation indicated that the hydrocarbon chain adopts a fully stretched conformation. JO - Science VL - 316 ER - TY - JOUR AU - Stuart, D.R. AU - Fagnou, K. PY - 2007 TI - The Catalytic Cross-Coupling of Unactivated Arenes SP - 1172-5 KW - Aromatics, catalytic cross-coupling Acetylindoles, N-, benzene cross-coupling AB - The industrially important coupling of arom. compds. has generally required differential prefunctionalization of the arene coupling partners with a halide and an electropos. group. Here we report that palladium, in conjunction with a copper oxidant, can catalyze the cross-coupling of N-acetylindoles and benzenes in high yield and high regioselectivity across a range of indoles without recourse to activating groups. These reactions are completely selective for arene cross-coupling, with no products arising from indole or benzene homo-coupling detected by spectroscopic anal. This efficient reactivity should be useful in the design of other oxidative arene cross-couplings as well. JO - Science VL - 316 ER - TY - JOUR AU - Yan, S. AU - Wu, Y.-T. AU - Zhang, B. AU - Yue, X.-F. AU - Liu, K. PY - 2007 TI - Do Vibrational Excitations of CHD3 Preferentially Promote Reactivity Toward the Chlorine Atom? SP - 1723-6 KW - Chlorine, vibrational energy AB - The influence of vibrational excitation on chem. reaction dynamics is well understood in triat. reactions, but the multiple modes in larger systems complicate efforts toward the validation of a predictive framework. Although recent expts. support selective vibrational enhancements of reactivities, such studies generally do not properly account for the differing amts. of total energy deposited by the excitation of different modes. By precise tuning of translational energies, we measured the relative efficiencies of vibration and translation in promoting the gas-phase reaction of CHD3 with the Cl atom to form HCl and CD3. Unexpectedly, we obsd. that C-H stretch excitation is no more effective than an equiv. amt. of translational energy in raising the overall reaction efficiency; CD3 bend excitation is only slightly more effective. However, vibrational excitation does have a strong impact on product state and angular distributions, with C-H stretch-excited reactants leading to predominantly forward-scattered, vibrationally excited HCl. JO - Science VL - 316 ER - TY - JOUR AU - Sabbah, H. AU - Biennier, L. AU - Sims, I.R. AU - Georgievskii, Y. AU - Klippenstein, S.J. AU - Smith, I.W.M. PY - 2007 TI - Understanding Reactivity at Very Low Temperatures: The Reactions of Oxygen Atoms with Alkenes SP - 102-5 KW - Alkenes, with O(3P), low temperatures Low temperature reactions AB - A remarkable no. of reactions between neutral free radicals and neutral mols. have been shown to remain rapid down to temps. as low as 20 K. The rate coeffs. generally increase as the temp. is lowered. We examd. the reasons for this temp. dependence through a combined exptl. and theor. study of the reactions of O(3P) atoms with a range of alkenes. The factors that control the rate coeffs. were shown to be rather subtle, but excellent agreement was obtained between the exptl. results and microcanonical transition state theory calcns. based on ab initio representations of the potential energy surfaces describing the interaction between the reactants. JO - Science VL - 317 ER - TY - JOUR AU - Melnick, J.G. AU - Parkin, G. PY - 2007 TI - Cleaving Mercury-Alkyl Bonds: A Functional Model for Mercury Detoxification by MerB SP - 225-7 KW - Organomercury, detoxification AB - The extreme toxicity of organomercury compds. that are found in the environment has focused attention on the mechanisms of action of bacterial remediating enzymes. Facile room-temp. protolytic cleavage by a thiol of the Hg-C bond in mercury-alkyl compds. that emulate the structure and function of the organomercurial lyase MerB is described. Specifically, the tris(2-mercapto-1-t-butylimidazolyl)hydroborato ligand [TmBut], which features three sulfur donors, has been used to synthesize [TmBut]HgR alkyl compds. (R = Me or ethyl) that react with phenylthiol (PhSH) to yield [TmBut]HgSPh and RH. Although [TmBut]HgR compds. exist as linear two-coordinate complexes in the solid state, 1H NMR spectroscopy indicates that the complexes exist in rapid equil. with their higher-coordinate [?2-TmBut]HgR and [?3-TmBut]HgR isomers in soln. Facile access to a higher-coordinate species is proposed to account for the exceptional reactivity of [TmBut]HgR relative to that of other two-coordinate mercury-alkyl compds. JO - Science VL - 317 ER - TY - JOUR AU - Iwasawa, T. AU - Hooley, R.J. AU - Rebek, J., Jr. PY - 2007 TI - Stabilization of Labile Carbonyl Addition Intermediates by a Synthetic Receptor SP - 493-6 KW - Hemiaminal intermediates, encapsulation AB - Products of unfavorable chem. equil. are not readily obsd. because their high energy and increased reactivity result in low concns. Biol. macromols. use binding forces to access unfavorable equil. and stabilize reactive intermediates by isolating them from the medium. In a similar vein, we describe here a synthetic receptor that allows direct observation of labile tetrahedral intermediates: hemiaminals formed in the reaction of an aldehyde carbonyl group with amines. The receptor encapsulates alkyl-substituted primary amines, then orients them toward a covalently tethered aldehyde function. The hemiaminal intermediates appear at high concn., confined from the bulk soln. and observable at ambient temp. by conventional NMR spectroscopy. JO - Science VL - 317 ER - TY - JOUR AU - Hamilton, G.L. AU - Kang, E.J. AU - Mba, M. AU - Toste, F.D. PY - 2007 TI - A Powerful Chiral Counterion Strategy for Asymmetric Transition Metal Catalysis SP - 496-9 KW - Chiral counterions, Au complexes Chiral anionic counterions AB - Traditionally, transition metal-catalyzed enantioselective transformations rely on chiral ligands tightly bound to the metal to induce asym. product distributions. High enantioselectivities conferred by a chiral counterion in a metal-catalyzed reaction are reported. Two different transformations catalyzed by cationic gold(I) complexes generated products in 90 to 99% enantiomeric excess with the use of chiral binaphthol-derived phosphate anions. Furthermore, the chiral counterion can be combined additively with chiral ligands to enable an asym. transformation that cannot be achieved by either method alone. This concept of relaying chiral information via an ion pair should be applicable to a vast no. of metal-mediated processes. JO - Science VL - 317 ER - TY - JOUR AU - Suzuki, T. AU - Ohta, E. AU - Kawai, H. AU - Fujiwara, K. AU - Fukushima, T. PY - 2007 TI - Dynamic Redox Systems as Electrochromic Materials: Bistability and Advanced Response SP - 851-69 KW - Redox systmes, dynamic Hexaphenylethane, dynamic redox system Butane-1,4-diyl dications AB - A review. 'Dynamic redox systems' is the name given to a certain class of compds. that can be reversibly converted into the corresponding charged species accompanied by C-C bond formation/cleavage upon electron transfer. This account details the two major motifs (hexaphenylethane derivs. and butane-1,4-diyl dications) that have been developed in the principal author's group. JO - Synlett ER - TY - JOUR AU - Meggers, E. AU - Atilla-Gokcumen, G.E. AU - Bregman, H. AU - Maksimoska, J. AU - Mulcahy, S.P. AU - Pagano, N. AU - Williams, D.S. PY - 2007 TI - Exploring Chemical Space with Organometallics: Ruthenium Complexes as Protein Kinase Inhibitors SP - 1177-89 KW - Ruthenium complexes, protein kinase inhibitors AB - A review. Complementing org. elements with a metal center provides new opportunities for building three-dimensional structures with unique and defined shapes. Such access to unexplored chem. space may lead to the discovery of mols. with unprecedented properties. Along these lines, this account article describes our successful design of highly potent and selective ruthenium-based inhibitors for the protein kinases GSK-3 and Pim-1 by using the class of indolocarbazole alkaloids as a lead structure. The described ruthenium complexes are kinetically inert scaffolds in which the ruthenium has the function to organize the orientation of the org. ligands in the three-dimensional space. JO - Synlett ER - TY - JOUR AU - Somfai, P. AU - Panknin, O. PY - 2007 TI - Investigations of the [2,3]-Sigmatropic Rearrangements of Vinylaziridines and Allylic Amines SP - 1190-202 KW - Vinylaziridines, [2,3]-sigmatropic rearrangement Amines, allylic, [2,3]-sigmatropic rearrangement AB - A review. This account summarizes our studies of [2,3]-sigmatropic rearrangements of vinylaziridines and allylic amines. The scope and limitations of the reactions as well as our present mechanistic understanding are also discussed. JO - Synlett ER - TY - JOUR AU - Hu, Q.-S. PY - 2007 TI - Controlling Competing Pathways in Palladium-Catalyzed Tandem/Domino Reactions of Hindered Grignard Reagents with 1,2-Dihaloarenes and 2-Haloaryl Tosylates SP - 1331-45 KW - Dihaloarenes, Grignard reagents, tandem reactions Haloaryl tosylates, Grignard reagents, tandem reactions Tandem reactions, transmetalation AB - A review. Based on the hypothesis that individual elementary steps in the catalytic cycle of Pd-catalyzed cross-coupling reactions could be controlled, we explored the opportunity of controlling the transmetalation step to develop new reactions. The results of these studies, summarized in this account, may lead to the development of other new tandem/domino reactions by using the same or similar concepts of controlling the transmetalation step and the palladium-assocd. aryne-generation strategy. JO - Synlett ER - TY - JOUR AU - Bertus, P. AU - Szymoniak, J. PY - 2007 TI - Titanium-Mediated Synthesis of Primary Cyclopropylamines from Nitriles and Grignard Reagents SP - 1346-56 KW - Cyclopropylamines, from nitriles and organomagnesium Cyclopentenylamines, synthesis Cyclopentenones, synthesis AB - This review presents studies on the development of a new method for the prepn. of primary cyclopropylamines. The established procedure is simple and the reaction appears to be quite general. A wide range of nitriles and organomagnesium reagents can react to afford diversely substituted cyclopropylamines. Furthermore, bicyclic cyclopropylamines can be obtained via an intramol. coupling from unsatd. nitriles. The reaction allows an easy prepn. of 1-aminocyclopropanecarboxylic acids and 1-aza spirocyclic compds. bearing a cyclopropane ring. The reaction can also be applied to the prepn. of polyfunctional and more complex org. mols. as exemplified with the synthesis of carbohydrates bearing aminocyclopropyl moieties and spirocyclopropyl pyrrolidines. During study of the title reaction, an unusual [4+1] cycloaddn. reaction to afford cyclopentenylamines or cyclopentenones has been discovered and is described. JO - Synlett ER - TY - JOUR AU - Walji, A.M. AU - MacMillan, D.W.C. PY - 2007 TI - Strategies to Bypass the Taxol Problem. Enantioselective Cascade Catalysis, A New Approach for the Efficient Construction of Molecular Complexity SP - 1477-89 KW - Taxol, cascade reactions AB - A review. Millions of years of evolution have allowed Nature to develop ingenious synthetic strategies and reaction pathways for the construction of architectural complexity. In contrast, the field of chem. synthesis is young with its beginnings dating back to the early 1800's. Remarkably, however, the field of chem. synthesis appears capable of building almost any known natural isolate in small quantities, yet we appear to be many years away from operational strategies or technologies that will allow access to complexity on a scale suitable for society's consumption. This essay attempts to define some of the issues that currently hamper our ability to efficiently produce complex mols. via large-scale total synthesis. In particular, issues such as 'regime of scale' and 'stop-and-go synthesis' are discussed in terms of a specific example (the taxol problem) and more broadly as they apply to the large-scale prodn. of complex targets. As part of this essay we discuss the use of enantioselective cascade catalysis as a modern conceptual strategy to bypass many of the underlying features that generally prevent total synthesis being utilized on a manufg. scale. Last we provide a brief review of the state of the art with respect to complex mol. prodn. via enantioselective cascade catalysis. JO - Synlett ER - TY - JOUR AU - Woodward, S. PY - 2007 TI - Design Versus Discovery in Synthetic Applications of Organoalanes SP - 1490-500 KW - Organoalanes Organoaluminum, with aldehydes Organoaluminum, with allylic halides AB - A review and discussion focusing on the benefits of considered fore-thought in proposing new asym. catalytic reactions is presented based on the author's experiences in the areas of Cu-promoted 1,4-addn. and SNW' chem. and in the area of Group 10 catalyzed coupling reactions of organoaluminium reagents with aldehydes and allylic halides. While high-throughput methods have become the norm for attaining practical procedures in catalytic asym. chem. appropriate strategic planning should not be abandoned in the conception of new catalytic processes. JO - Synlett ER - TY - JOUR AU - Oestreich, M. PY - 2007 TI - Silicon-Stereogenic Silanes in Asymmetric Catalysis SP - 1629-43 KW - Silanes, Si-stereogenic AB - A review. The exploitation of chirality at silicon in asym. catalysis is a challenging task. Silicon-stereogenic silanes were initially utilized to elucidate the stereochem. course of substitution at silicon. These mechanistic investigations are to be seen alongside a handful of synthetic transformations with covalently bound silicon as the stereo-inducer. While in these substrate-controlled reactions the asym. substituted silicon functions as a chiral auxiliary, reagent-controlled processes have remained elusive. This account summarizes the aimed design of silicon-stereogenic silanes and their introduction to stereoselective synthesis as chiral reagents. JO - Synlett ER - TY - JOUR AU - Hall, D.G. PY - 2007 TI - Lewis and Bronsted Acid Catalyzed Allylboration of Carbonyl Compounds: from Discovery to Mechanism and Applications SP - 1644-55 KW - Allylboration, of carbonyls Carbonyl allylation, allylic borates AB - A review. The recent development of Lewis and Bronsted acid catalyzed manifolds for the allylboration of carbonyl compds. has opened doors towards an ideal carbonyl allylation methodol. using stable and nontoxic allylic boronates as reagents. This Account relates our lab.'s discovery of acid-catalyzed allylborations, mechanistic investigations of these new processes, and ongoing efforts by our group and others towards a general catalytic enantioselective allylboration methodol. JO - Synlett ER - TY - JOUR AU - Rajca, A. AU - Rajca, S. AU - Pink, M. AU - Miyasaka, M. PY - 2007 TI - Annelated, Chiral .p.-Conjugated Systems: Tetraphenylenes and Helical .b.-Oligothiophenes SP - 1799-822 KW - Tetraphenylenes Oligothiophenes Helicenes AB - A review. Compds. with highly annelated, chiral .p.-systems, such as tetraphenylenes and [n]helicenes, are known to possess strong chiral properties and high configurational stability, which are prerequisites for many chiral materials. This account describes the unfolding story about our research on the synthesis and x-ray crystallog. characterization of functionalized nonracemic tetraphenylenes and helical .b.- oligothiophenes, as well as related [n]helicene derivs. JO - Synlett ER - TY - JOUR AU - Tanaka, K. PY - 2007 TI - Cationic Rhodium(I)/BINAP-Type Bisphosphine Complexes: Versatile New Catalysts for Highly Chemo-, Regio-, and Enantioselective [2+2+2] Cycloadditions SP - 1977-93 KW - Rhodium, BINAP biphosphine complexes Cycloadditions, [2+2+2] AB - A review. Our research group was the first to discover that cationic rhodium(I)/BINAP-type bisphosphine complexes are versatile new catalysts for highly chemo-, regio-, and enantioselective [2+2+2] cycloaddns. The high chemo- and regioselectivity of these cycloaddns. enabled efficient catalytic synthesis of substituted benzenes, cyclophanes, and nitrogen heterocycles. Furthermore, enantioselective variants of these cycloaddns. were also developed that realized efficient catalytic constructions of axial, planar, central, and spiro chirality. JO - Synlett ER - TY - JOUR AU - Patil, N.T. AU - Yamamoto, Y. PY - 2007 TI - Palladium-Catalyzed Cascade Reactions of Highly Activated Olefins SP - 1994-2005 KW - Alkenes, cascade reactions AB - A review. In this account, we describe the use of highly activated olefins for palladium-catalyzed reactions. Particularly noteworthy is the creation of new processes using such activated olefins and the efficiency of those processes in building carbon-carbon and carbon-heteroatom bonds JO - Synlett ER - TY - JOUR AU - Gil, M.V. AU - Arevalo, M.J. AU - Lopez, O. PY - 2007 TI - Click Chemistry - What's in a Name? Triazole Synthesis and Beyond SP - 1589-620 KW - Cycloaddition, 1,3-dipolar Epoxides, click chemistry Aziridines, click chemistry AB - A review. The environmentally amiable route to C-heteroatom bond formation, described by Sharpless as 'click chem.', has become known as a fast, efficient, and reliable approach to the synthesis of novel compds. with desired functionalities. Readily available starting materials must be used in this methodol. and they should be essentially inert to most biol. and org. conditions, including H2O and O2. In this review, the authors cover reactions included in this label such as Huisgen 1,3-dipolar cycloaddns., nucleophilic ring-opening reactions of strained rings such as epoxides and aziridines, and amide synthesis, as well as their applications in org. synthesis, mol. biol., macromol. chem. and materials science. Other topics discussed include click synthesis of epoxides and aziridines, supramol. click chem., liq. crystals, self-assembled monolayers, multicomponent reactions, creating drug candidates under click conditions, click chem. with peptides and proteins and DNA as a participant in click reactions. JO - Synthesis ER - TY - JOUR AU - Auge, J. AU - Lubin-Germain, N. AU - Uziel, J. PY - 2007 TI - Recent Advances in Indium-Promoted Organic Reactions SP - 1739-64 KW - Indium catalysts Organoindium catalysts AB - This review deals with org. reactions which are promoted by indium metal or indium salts, with a focus on recent advances in stoichiometric and catalytic pathways. Applications to transmetalations, cross-coupling reactions and carboindation, in which an organoindium species may be postulated, are highlighted, as well as the reactions in which a radical is the key intermediate. Special attention is placed on the role of indium metal as a reducer, and on the Lewis acidity of indium salts in catalytic processes. JO - Synthesis ER - TY - JOUR AU - Hemeon, I. AU - Bennet, A.J. PY - 2007 TI - Sialic Acid and Structural Analogues: Stereoselective Syntheses SP - 1899-926 KW - Sialic Acid AB - This review describes various synthetic strategies developed for the synthesis of sialic acid and its variants at each position on the carbon skeleton. Sialic acid (N-acetylneuraminic acid) is a carbohydrate that is often found on the ends of oligosaccharide chains in biol. systems. As such, it is important in several biol. recognition/communication events mediated by sialic acid recognizing proteins that play integral roles in these phenomena. It is therefore necessary to develop synthetic routes to sialic acid and its derivs. and analogs. Many of these routes have led to compds. used as enzyme inhibitors for treatment of disease states and also as probes of biol. relevant binding events and of the mechanisms of enzyme action. Every position on the nine-carbon backbone of sialic acid has been derivatized for such purposes, being synthesized both chemoenzymically and chem. from precursors ranging from non-carbohydrate sources to sialic acid itself. JO - Synthesis ER - TY - JOUR AU - Bellina, F. AU - Cauteruccio, S. AU - Rossi, R. PY - 2007 TI - Synthesis and Biological Activity of Vicinal Diaryl-Substituted 1H-Imidazoles SP - 4571-624 KW - Imidazoles, diaryl AB - A review. Imidazoles are common scaffolds in highly significant biomols., including biotin, histidine, histamine, the pilocarpine alkaloids, etc. They also have been found to possess many pharmacol. properties and are widely implicated in biochem. processes. The topics covered in this review (401 ref.) include: (i) a crit. summary of the methods reported in the literature (up to the end of June 2006) for the synthesis of 1,2-,1,5-, and 4,5-diaryl-1H-imidazoles; 1,2,4-, 1,2,5-, and 2,4,5-triaryl-1H-imidazoles and 1,2,4,5-tetraaryl-1H-imidazoles; and. (ii) a survey of the literature data on the biol. properties of these heterocycles. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Hartley, R.C. AU - Li, J. AU - Main, C.A. AU - McKiernan, G.J. PY - 2007 TI - Titanium Carbenoid Reagents for Converting Carbonyl Groups into Alkenes SP - 4825-64 KW - Alkenes, from carbonyls, Ti carbenoids Titanium carbenoids AB - A review. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Lepore, S.D. AU - Mondal, D. PY - 2007 TI - Recent Advances in Heterolytic Nucleofugal Leaving Groups SP - 5103-22 KW - Sulfonate leaving groups Carboxylate leaving groups AB - A review. This review begins with a discussion of advances in sulfonate and carboxylate-based leaving groups. Also included are organometallic leaving groups, heterocyclic leaving groups, activation-deactivation leaving groups, and nucleophile assisting leaving groups. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Padwa, A. AU - Bur, S.K. PY - 2007 TI - The Domino Way to Heterocycles SP - 5341-78 KW - Domino reactions, heterocycle synthesis AB - A review. This review contains a representative sampling from the last 15 years of the kinds of reactions that have been sequenced into cascades to produce heterocyclic mols. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Lenardao, E.J. AU - Botteselle, G.V. AU - De Azambuja, F. AU - Perin, G. AU - Jacob, R.G. PY - 2007 TI - Citronellal as Key Compound in Organic Synthesis SP - 6671-712 KW - Citronellal AB - A review. Citronellal is an attractive compd. in org. synthesis for several reasons: it is easily available from natural sources (e.g., from citronella and eucalyptus oil) or synthetically prepd. (Takasago process); it is cheap and both enantiomers are available with high degrees of purity. Citronellal is a key compd. in numerous org. syntheses for the insertion and/or induction of chirality in more complex naturally or non-naturally occurring mols. When citronellal is used in one of its pure forms (R or S), it is possible to prep. chiral mols. with high enantioselectivity, while avoiding expensive and tedious sepn. and purifn. steps. These synthetic aspects match with several green chem. principles and make citronellal an excellent tool for the implementation of cleaner and environmentally benign processes. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Polshettiwar, V. AU - Molnar, A. PY - 2007 TI - Silica-supported Pd Catalysts for Heck Coupling Reactions SP - 6949-76 KW - Heck coupling, with supported Pd AB - A review is presented in which is discussed a variety of silica-supported palladium catalysts for Heck coupling reactions. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Muzart, J. PY - 2007 TI - Aldehydes from Pd-Catalyzed Oxidation of Terminal Olefins SP - 7505-21 KW - Aldehydes, from terminal alkenes Styrene, Wacker oxidation Phenylacetaldehyde, from styrene AB - A review dealing with the prepn. of aldehydes by Pd-catalyzed oxidn. of terminal olefins; for example, the oxidn. of styrene under Wacker-type conditions leads to acetophenone, phenylacetaldehyde and its decompn. product, i.e., benzaldehyde; recently, Spencer et al. have disclosed exptl. conditions leading efficiently to phenylacetaldehyde from styrene. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Druzhinin, S.V. AU - Balenkova, E.S. AU - Nenajdenko, V.G. PY - 2007 TI - Recent Advances in the Chemistry of .a.,.b.-Unsaturated Trifluoromethylketones SP - 7753-808 KW - Trifluoromethylketones, unsaturated AB - This review presents the recent advances on the synthesis of .a.,.b.-unsatd. trifluoromethylketones and their use the prepn. of 3 through 7 membered ring heterocycles. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Wagner, F.F. AU - Comins, D.L. PY - 2007 TI - Recent Advances in the Synthesis of Nicotine and its Derivatives SP - 8065-82 KW - Nicotine, synthesis AB - This review presents progress in the synthesis of nicotine and analogs along with some seminal earlier work. Significant advances were made in the last 10 years that have increased the availability of analogs for pharmacol. study. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Yamamoto, H. PY - 2007 TI - New Reaction and New Catalyst - A Personal Perspective SP - 8377-412 KW - Lewis acids, Al, B, Sn, in new syntheses Bronsted acids, combined with Lewis acids AB - A review. A no. of new synthetic methods are reviewed. Most of the methods are based on aluminum, boron, tin, silver Lewis acids and/or Bronsted acid catalysts. Concepts of combined acid catalysis and super Bronsted acid catalysis are also summarized. These methods are useful for selective org. transformations including simple natural product synthesis. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Popowycz, F. AU - Merour, J.-Y. AU - Joseph, B. PY - 2007 TI - Synthesis and Reactivity of 4-, 5- and 6-Azaindoles SP - 8689-707 KW - Azaindoles AB - A review. The synthesis and reactivity of 4-, 5-, and 6-azaindoles, updated from 2000, are covered. Among the synthetic methods are the Reissert synthesis, Batcho-Leimgruber synthesis, Hemetsberger-Knittel synthesis, and the Bartoli synthesis. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Taylor, C.M. AU - Wang, W. PY - 2007 TI - Histidinoalanine: A Crosslinking Amino Acid SP - 9033-47 KW - Histidinoalanine AB - A review. Histidinoalanine, a protein crosslink, has been found in milk products that have been heated and/or treated with alkali. It is also found in human tissue, including connective tissue, bone, dentin and eye cataracts, in phosphoproteins of bivalve mollusks, and in theonellamides, a family of bicyclic dodecapeptides. This review discusses the mechanism of formation of histidinoalanine in the above biol. categories, and the different methods of its chem. synthesis. JO - Tetrahedron VL - 63 ER - TY - JOUR AU - Wannberg, J. AU - Ersmark, K. AU - Larhed, M. PY - 2006 TI - Microwave-Accelerated Synthesis of Protease Inhibitors SP - 167-98 KW - Protease inhibitors, microwave synthesis Microwaves, protein inhibotor synthesis AB - A review. Controlled microwave heating has recently emerged as an enabling and productivity-enhancing tool for the medicinal chemist. With this superheating method, reaction times can often be reduced from days and hours down to minutes, and chem. previously considered impractical or unattainable can be accessed. In this review, the search for new protease inhibitors using microwave-assisted small-scale org. transformations is presented, with a special focus on the development of inhibitors of the aspartic proteases plasmepsin I, plasmepsin II, and HIV-1 protease. A series of rapid lead-optimizations starting from transition-state mimicking core scaffolds using mainly microwave-accelerated, palladium-catalyzed coupling reactions are presented. Biol. background and test results are summarized. JO - Topics in Current Chemistry VL - 266 ER - TY - JOUR AU - Haase, C. AU - Seitz, O. PY - 2007 TI - Chemical Synthesis of Glycopeptides SP - 1-36 KW - Glycopeptides, synthesis Protein glycosylation AB - A review. Despite its omnipresence in nature, comparatively little is known about how glycosylation affects the function and activity of proteins. To understand the role of protein glycosylation at the mol. level, it is important to have access to homogeneous glycoproteins and glycopeptides. Chem. synthesis is particularly suited to provide uniform glycoprotein material, thus playing a pivotal role for the advancement of glycobiol. This chapter summarizes the recent progress achieved in glycopeptide synthesis including new glycosylation methods, enzymic transformations, chemoselective ligation and recombinant expression. JO - Topics in Current Chemistry VL - 267 ER - TY - JOUR AU - Thayer, D.A. AU - Wong, C.-H. PY - 2007 TI - Enzymatic Synthesis of Glycopeptides and Glycoproteins SP - 37-63 KW - Glycopeptides, enzymatic synthesis Glycoproteins, enzymatic synthesis AB - A review. Glycosylation is recognized as important in biol., though the discovery of previously unknown functions assocd. with carbohydrates is ongoing. As the most complex and diverse post-translational modification, detg. the structure-function relationships for glycosylation remains difficult due to the heterogeneous expression of glycoproteins as mixts. of glycoforms. Thus the synthesis of glycoproteins and glycopeptides with defined glycan structures is essential for detailed detn. of the role of glycosylation. This review describes the use of enzymes for the synthesis of glycopeptides and glycoproteins, including their use as catalysts for glycosidic linkage formation and elaboration, peptide bond formation, and modification. Topics in Current Chem. (2007) 267: 37-63 (Springer Verlag;, Berlin Heidelberg 2006). JO - Topics in Current Chemistry VL - 267 ER - TY - JOUR AU - Meyer, B. AU - Moeller, H. PY - 2007 TI - Conformation of Glycopeptides and Glycoproteins SP - 187-251 KW - Glycopeptides, conformation Glycoproteins, conformation Proteins, glycosylation AB - A review. Glycosylation is the most frequent post-translational modification found in proteins. Glycoproteins are involved in a highly diverse spectrum of biol. functions, ranging from protein folding and mol. and cellular recognition to attack of pathogens and regulation of biol. half-life. Consequently, understanding the structural role of glycosylation provides key insight into biol. processes as well as ideas for medicinal applications. Here, the authors review the current methodol. to arrive at high-resoln. structures of glycopeptides and glycoproteins. To achieve this, significant obstacles have to be overcome like prepn. of sufficient amts. of sufficiently pure and homogeneous material, analyzing highly ambiguous spectroscopic data, and dealing with mols. that show local or global disorder. The authors provide an overview of their knowledge of glycoprotein and glycopeptide structure, and illustrate with selected examples the performance and limitations of current methodol. JO - Topics in Current Chemistry VL - 267 ER - TY - JOUR AU - Fischer, D. AU - Geyer, A. PY - 2007 TI - NMR Analysis of Bioprotective Sugars: Sucrose and Oligomeric (1 --> 2)-.a.-D-Glucopyranosyl-(1 --> 2)-.b.-D-Fructofuranosides SP - 169-85 KW - Bioprotectants, sugar, NMR AB - A review. NMR spectroscopy yields structural information on a new class of bioprotectants with the general compn. oligo(1?2)-.a.-D- glucopyranosyl-(1?2)-.b.-D-fructofuranoside. Their smallest representative is sucrose for which conflicting models try to explain its cryoprotective properties. Starting from sucrose, we characterize the influence of the growing chain of oligo(1?2)-.a.-D- glucopyranoses. An anal. approach will be presented that can identify ultraweak membrane affinities, a property often discussed in the context of cryoprotectants. The most prominent feature of the vicinally connected (1?2)-.a.-D-glucopyranose oligomers is their well-defined soln. structure with a stand-alone sugar helix. The unfolding barrier of this helix is large enough to become observable as line-broadening in the 1H NMR. JO - Topics in Current Chemistry VL - 272 ER - TY - JOUR AU - Bur, S.K. PY - 2007 TI - 1,3-Sulfur Shifts: Mechanism and Synthetic Utility SP - 125-71 KW - Sulfur shifts, 1,3- AB - A review. While allylic migrations are known, 1,3-sulfur shifts are relatively rare. These shifts occur through a variety of mechanisms depending upon the substrate type and the reaction conditions. Radical-chain, ion-pair, dipolar, and symmetry-forbidden 1,3-sigmatropic mechanisms have all been proposed. Allylic sulfur shifts were used in the synthesis of sulfides and sulfones of higher complexity, the stereospecific synthesis of alkenes, and the construction of ketones. This comprehensive survey of 1,3-sulfur migrations pays particular attention to the reported mechanisms and synthetic application. JO - Topics in Current Chemistry VL - 274 ER - TY - JOUR AU - Reggelin, M. PY - 2007 TI - [2,3]-Sigmatropic Rearrangements of Allylic Sulfur Compounds SP - 1-65 KW - Rearrangements, with sulfur AB - A review. Nine variations of [2,3]-sigmatropic rearrangements of allylic S compds. are reviewed with particular emphasis on newer developments and applications in target mol. oriented research. JO - Topics in Current Chemistry VL - 275 ER - TY - JOUR AU - Braverman, S. AU - Cherkinsky, M. PY - 2007 TI - [2,3]Sigmatropic Rearrangements of Propargylic and Allenic Systems SP - 67-101 KW - Propargyl sulfonium ylides, rearrangements Rearrangements, with sulfur AB - A review. [2,3]Sigmatropic rearrangements of propargyl sulfonium ylides along with recent advances in the corresponding sulfenate-sulfoxide and sulfinate-sulfone type rearrangements are reviewed. Some new addnl. examples of these types of transformations, including rearrangements of propargylic dialkoxy disulfides are also surveyed. JO - Topics in Current Chemistry VL - 275 ER - TY - JOUR AU - Fernandez de la Pradilla, R. AU - Tortosa, M. AU - Viso, A. PY - 2007 TI - Sulfur Participation in [3,3]-Sigmatropic Rearrangements SP - 103-29 KW - Thio-Claisen rearrangement Rearrangements, with sulfur AB - A review. The thio-Claisen rearrangement is a general and facile process that is often advantageous over the std. Claisen rearrangement. Several asym. variants of the thio-Claisen rearrangement are reported. The rearrangement of sulfonium salts and sulfoxides takes place even more readily. Alkenyl sulfoxides and sulfilimines undergo a highly stereo-controlled cyclization to lactones and lactams, resp., upon reaction with haloketenes; this synthetically useful process entails a [3,3]-sigmatropic rearrangement of a zwitterionic intermediate. S-contg. functionalities located at the periphery of the Claisen substrates exert a powerful influence on the outcome of the process. JO - Topics in Current Chemistry VL - 275 ER - TY - JOUR AU - Zonta, C. AU - De Lucchi, O. AU - Volpicelli, R. AU - Cotarca, L. PY - 2007 TI - Thione-Thiol Rearrangement: Miyazaki-Newman-Kwart Rearrangement and Others SP - 131-61 KW - Thione-thiol rearrangement Miyazaki-Newman-Kwart rearrangement Aromatic thiols, from phenols Rearrangements, with sulfur AB - A review. Thione-to-thiol rearrangements represent a general route for the synthesis of S compds. from hydroxyl functionalities. In particular, the Miyazaki-Newman-Kwart rearrangement was widely used for the synthesis of arom. thiols from the corresponding phenols. JO - Topics in Current Chemistry VL - 275 ER - TY - JOUR AU - Plesniak, K. AU - Zarecki, A. AU - Wicha, J. PY - 2007 TI - The Smiles Rearrangement and the Julia-Kocienski Olefination Reaction SP - 163-250 KW - Sulfur, catalysts, rearrangements Julia-Kocienski olefination Aromatic ring dislocation Rearrangements, with sulfur AB - A review. Mol. rearrangements consisting of base- or acid-induced dislocation of arom. or heteroarom. rings are reviewed. The emphasis is given to recent developments and, in particular, to synthetic application of the rearrangement. A novel classification was applied to discuss systematically rather diverse published data. The rearrangements are reviewed according to atoms entering and leaving the ipso-position of the migrating ring. The Julia-Kocienski olefination reaction is presented in other parts of this vol. JO - Topics in Current Chemistry VL - 275 ER - TY - JOUR AU - Kuhn, L.T. AU - Bargon, J. PY - 2007 TI - Transfer of Parahydrogen-Induced Hyperpolarization to Heteronuclei SP - 25-68 KW - NMR, in situ AB - A review. Homogeneously catalyzed hydrogenation reactions of unsatd. substrates with H2 gas mixts. enriched in parahydrogen yield strong NMR signal enhancements of the transferred 1H nuclei if the symmetry of H2 is broken in the resulting hydrogenated products. This chem. induced hyperpolarization phenomenon known as parahydrogen-induced polarization (PHIP) is a well-established polarization technique in NMR spectroscopy. Ever since its theor. prediction and subsequent exptl. verification the method was used to increase signal intensity in 1H-NMR spectroscopy for the elucidation of catalytic pathways of hydrogenation reactions and their kinetic behavior. Also, PHIP is not confined to the attached protons and 1H nuclei which are close to the hydrogenation site but it can also be transferred spontaneously to heteronuclei, which are present in the hydrogenation product. In this review the authors give an overview of the different expts. that were performed in recent years to efficiently transfer PHIP-derived polarization to insensitive magnetically active nuclei following the catalyzed parahydrogenation of their unsatd. precursor mols. A detailed description of the expts. dealing with every individual heteronucleus in particular is followed by a discussion of the mechanisms leading to PHIP transfer. Subsequently, the authors describe the existing set of pulse sequences that were designed and successfully employed to induce an exchange of increased magnetization originating from PHIP between protons and heteronuclei using conventional coherence transfer schemes. Finally, possible applications of nonproton PHIP spectroscopy in medicine and clin. research are outlined. JO - Topics in Current Chemistry VL - 276 ER - TY - JOUR AU - Greiner, L. AU - Laue, S. AU - Woeltinger, J. AU - Liese, A. PY - 2007 TI - Continuous Asymmetric Hydrogenation SP - 111-24 KW - Hydrogenation, continuous NMR, in situ AB - A review. Asym. hydrogenation with homogeneous sol. catalysts is a key technol. for the prodn. of enantiomerically enriched fine chems. Hydrogen supply via dense membranes in combination with continuous membrane filtration of sol. macromol. catalysts allows for continuous hydrogenation. A optimized reactor with minimized vol. was realized and used for continuous enzymic and homogeneous catalysis. The vital importance of catalyst stability for continuous application is discussed. Also, activation kinetics of the Pyrphos catalyst was studied and is dependent on the presence of substrate. JO - Topics in Current Chemistry VL - 276 ER - TY - JOUR AU - Kuhn, L.T. AU - Bargon, J. PY - 2007 TI - Exploiting Nuclear Spin Polarization to Investigate Free Radical Reactions via in situ NMR SP - 125-54 KW - NMR, in situ, free radicals AB - A review. In situ NMR spectroscopy can be applied to study chem. reactions during which free radicals occur as intermediates. In chem. systems of low mol. wt., nuclear spin polarization results from the spin selectivity of free radical reactions because a pair of radicals, like any other given set of particles, has to obey the exclusion principle. Therefore, this system reacts selectively in terms of the participating nuclear spins when forming a chem. single bond. As a consequence, strong transient absorption and emission lines occur in NMR spectra acquired during a reaction of free radicals. This extraordinary phenomenon has become known as chem. induced dynamic nuclear polarization (CIDNP). Ever since its exptl. discovery and theor. verification, CIDNP was employed to study the mechanisms of free radical reactions in soln. As such it proved to be a very valuable tool for the elucidation of the mechanism of these reactions and, more importantly, to discriminate reaction pathways that include the formation of transient radical species from those that exclusively follow a diamagnetic route, i.e., a pathway where no paramagnetic intermediates are formed whatsoever. More recently, the photo-CIDNP technique also was employed extensively to probe the surface-accessibility of arom. amino acid side-chains bound within a protein. As such, it can be used to study the dynamic features of a protein during folding, refolding, and also in the equil. or steady state, yielding both qual. and quant. information. This review outlines the historical development of the CIDNP technique as well as its theor. background. This is followed by examples showing how CIDNP can be used to elucidate reaction pathways of chem. transformations comprising diamagnetic intermediates. Addnl., the authors present examples of how biol. CIDNP expts. are usually performed and the authors show what kind of information can be extd. JO - Topics in Current Chemistry VL - 276 ER -