Cycloisomerization Reactions Catalyzed by Transition Metal Complexes PDF Download
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Author: Erica Benedetti
Publisher:
ISBN:
Category :
Languages : en
Pages : 351
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Book Description
Ces dernières années, le besoin de méthodes éco-compatibles pour la préparation d'une vaste gamme de produits chimiques requis par la société a poussé la recherche à développer de nouveaux procédés de synthèse qui soient plus efficaces et économiques. Afin de minimiser l'utilisation de matières premières et la production de déchets, une réaction chimique devrait procéder selon les principes d'économie d'atomes. Plus précisément, une séquence synthétique devrait idéalement avoir lieu avec un contrôle complet de la stéréochimie, de manière quantitative et sans formation de produits secondaires. Les réactions de cyclisation des systèmes polyinsaturés, catalysées par les métaux de transition, offrent une opportunité réelle d'atteindre les objectifs exposés ci-dessus. Dans cette thèse, quatre différentes classes de réactions de cyclisation, catalysées par les métaux de transition, ont été traitées: (1) les métathèses des dienes et des énynes, (2) les carbonylations de Pauson-Khand, (3) l'activation électrophile d'alcynes catalysée par l'iridium et (4) les cycloisomerizations d'allènes catalysées par l'or. Ces méthodologies, qui ont permis d'obtenir une haute complexité moléculaire en une seule étape de synthèse, ont été utilisées avec succès pour la formation de nombreux composés hétérocycliques oxygénés et azotés. Des études, qui décrivent la large applicabilité de ces réactions, sont publiées avec un rythme très rapide. Dans le futur, la découverte de nouvelles transformations catalysées par les métaux de transition continuera sûrement à occuper un rôle central dans la synthèse organique.
Author: Erica Benedetti
Publisher:
ISBN:
Category :
Languages : en
Pages : 351
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Book Description
Ces dernières années, le besoin de méthodes éco-compatibles pour la préparation d'une vaste gamme de produits chimiques requis par la société a poussé la recherche à développer de nouveaux procédés de synthèse qui soient plus efficaces et économiques. Afin de minimiser l'utilisation de matières premières et la production de déchets, une réaction chimique devrait procéder selon les principes d'économie d'atomes. Plus précisément, une séquence synthétique devrait idéalement avoir lieu avec un contrôle complet de la stéréochimie, de manière quantitative et sans formation de produits secondaires. Les réactions de cyclisation des systèmes polyinsaturés, catalysées par les métaux de transition, offrent une opportunité réelle d'atteindre les objectifs exposés ci-dessus. Dans cette thèse, quatre différentes classes de réactions de cyclisation, catalysées par les métaux de transition, ont été traitées: (1) les métathèses des dienes et des énynes, (2) les carbonylations de Pauson-Khand, (3) l'activation électrophile d'alcynes catalysée par l'iridium et (4) les cycloisomerizations d'allènes catalysées par l'or. Ces méthodologies, qui ont permis d'obtenir une haute complexité moléculaire en une seule étape de synthèse, ont été utilisées avec succès pour la formation de nombreux composés hétérocycliques oxygénés et azotés. Des études, qui décrivent la large applicabilité de ces réactions, sont publiées avec un rythme très rapide. Dans le futur, la découverte de nouvelles transformations catalysées par les métaux de transition continuera sûrement à occuper un rôle central dans la synthèse organique.
Author: Valentine P. Ananikov
Publisher: Springer
ISBN: 364233735X
Category : Science
Languages : en
Pages : 377
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Book Description
Valentine P. Ananikov, Irina P. Beletskaya: Alkyne and alkene insertion into metal-heteroatom and metal-hydrogen bonds – the key stages of hydrofunctionalization process.- Akihiko Ishii* and Norio Nakata: The Mechanism for Transition Metal-Catalyzed Hydrochalcogenation of Unsaturated Organic Molecules.- A. L. Reznichenko and Kai C. Hultzsch: Early Transition Metal (Group 3-5, Lanthanides and Actinides) and Main Group Metal (Group 1, 2, and 13) Catalyzed Hydroamination.- Naoko Nishina and Yoshinori Yamamoto: Late transition metal catalyzed hydroamination.- Sumod A. Pullarkat and Pak-Hing Leung: Chiral Metal Complex Promoted Asymmetric Hydrophosphinations.- Masato Tanaka: Recent Progress in Transition Metal-Catalyzed Addition Reactions of H-P(O) Compounds with Unsaturated Carbon Linkages.- Christian Bruneau: Group 8 metals-catalyzed O-H bond addition to unsaturated molecules.- Giorgio Abbiati, Egle M. Beccalli, Elisabetta Rossi: Groups 9 and 10 metals-catalyzed O-H bond addition to unsaturated molecules.- Núria Huguet and Antonio M. Echavarren: Gold-Catalyzed O-H Bond Addition to Unsaturated Organic Molecules.- Akiya Ogawa: Transition-Metal-Catalyzed S-H and Se-H Bonds Addition to Unsaturated Molecules.
Author: Rachel Motove Zeldin
Publisher:
ISBN:
Category :
Languages : en
Pages : 532
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Book Description
The modern era of synthetic chemistry can be characterized by increased understanding, development and application of transition metal complexes to traditionally organic transformations. While the field has focused largely on the chemistry of group 4-8 metals (and in particular, rhodium and palladium), there has been growing interest in the past decade in using so-called "coinage metals"--Gold, silver and copper--as catalysts for organic reactions. Gold(I) metal complexes have been shown to effect a range of organic transformations that proceed through [pi]-activation mechanisms, often with greater selectivity than other transition metal complexes. Additionally, in contrast to more established transition metal reactions, gold(I) processes can be conducted at low temperature and in the presence of water and air. Because of their mild conditions and high degree of control, gold(I) reactions are ideal for application to total synthesis. In the first chapter of this text, we discuss the current state of the art of gold(I)-catalysis in the context of complex molecule synthesis. The reactivity exhibited by gold(I) complexes is highly controlled by choice of catalyst ligand. In the second chapter, we discuss the development of ligand-controlled intramolecular reaction of dienes and allenes to afford selectively either [4+2]- or [4+3] cycloadducts. The purpose of this discussion is two-fold: first, to demonstrate the effect that stabilization of reactive intermediates has on the course of gold(I) reactions, and second, to develop methodologies aimed at constructing novel, complex ring structures. In the third chapter of this text, we take one of the reactions discovered in the course of our work in diene-allene cycloadditions and apply it to the total synthesis of antimalarial bisindole alkaloids flinderoles B and C. The key step, a gold(I)-catalyzed hydroarylation of an allene using a C2-indole nucleophile, simulatenously installs three of four unique structural motifs of this natural product.
Author: András Kotschy
Publisher: Springer Science & Business Media
ISBN: 9781402036248
Category : Science
Languages : en
Pages : 224
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Book Description
"Heterocycles from Transition Metal Catalysis: Formation and Functionalization" provides a concise summary of the prominent role of late transition metal (palladium, nickel, copper) catalysed processes in the synthesis and functionalization of heterocyclic systems. It gives an introduction to catalytic transformations, an overview of the most important reaction types, and presents synthetically useful catalytic processes classified by the target system and the type of transformation. The book provides a representative selection of transition metal catalysed reactions transformations that are relevant in heterocyclic chemistry. In this way, the authors present a useful resource for members of the academic community looking for a textbook as well as industrial chemists in search of a reference book. This book will be an invaluable resource for synthetic chemists, medicinal chemists, and those more generally interested in applied catalysis.
Author: Louis S. Hegedus
Publisher: University Science Books
ISBN: 9781891389047
Category : Science
Languages : en
Pages : 358
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Book Description
This second edition offers easy access to the field of organotransition metal chemistry. The book covers the basics of transition metal chemistry, giving a practical introduction to organotransition reaction mechanisms.
Author: Shana Jocette Sturla
Publisher:
ISBN:
Category :
Languages : en
Pages : 428
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Book Description
(Cont.) generating [alpha]-silyl cyclopentenones. The 2,6-substituted aryloxide ligands allowed for modulation of steric and electronic parameters. Chapter 4. A complex formed from dicobalt octacarbonyl and a chiral aryl bisphosphite served as a catalyst for the intramolecular asymmetric Pauson-Khand reaction. Bicyclic cyclopentenones were obtained in up to 75% enantiomeric excess. For a terminal 1,6-enyne, the incremental enantiomeric excess was found to increase from 4-26% over the course of the reaction. The scope of this process was examined for a variety of 1,6- and 1,7-enynes, and a moderate degree of enantioselectivity was maintained only in the case of aryl-substituted 1,6-enynes.
Author: Michael Christian Ryan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Using transition metal catalysis to rapidly increase complexity for the construction of small molecules has been one of the most important areas of research in the field of synthetic organic chemistry. In particular, cyclopentadienylruthenium (CpRu) catalysis has previously been shown by our research group and others to be a selective, cost-effective, and atom-economical means of achieving this goal. In an effort to extend CpRu catalysis to enantioselective variants of these reactions, our group had previously developed CpRu complexes containing tethered chiral sulfoxides for their successful application towards asymmetric allylic substitution reactions. This work describes our efforts to expand the chemistry of these CpRu-sulfoxide complexes and to synthesize novel chiral CpRu and indenylruthenium (IndRu) catalysts for the discovery of new catalytic asymmetric cyclization reactions. CpRu-sulfoxide complexes were used to perform an asymmetric redox bicycloisomerization reaction that constructed [3.1.0] and [4.1.0] bicycles from propargyl alcohols. Initial reaction optimization was performed on 1,7-enynes due to the products' similarity to known triple-reuptake inhibitor GSK1360707. CpRu complex containing a tethered para-methoxy sulfoxide ligand proved to be the optimal catalyst for this reaction. Variation of the 1,7-enyne substrate structure revealed that a bulky 2,4,6-triisopropylbenzenesulfonyl (Tris) protecting group on the nitrogen-containing backbone was essential for observing high enantioselectivities for [4.1.0] bicycles. While THF proved to be the optimal solvent for redox isomerization of [4.1.0] bicycles, acetone provided the best results for [3.1.0] bicycles. Enantiomeric ratios as high as 98.5:1.5 were observed with Tris-containing [3.1.0] bicycles. The chemistry could be extended to 1,6-enynes containing other substrate tethers, including tosyl, diphenyl phosphoramidate, and dibenzyl malonate tethers. Nitrogen protecting groups were shown to be removable under reducing conditions. Catalysis performed with enantiomerically enriched propargyl alcohols revealed a matched/mismatched effect that was strongly dependent on the nature of the solvent. To the best of our knowledge, this methodology was the first example of a ruthenium-catalyzed asymmetric cycloisomerization reaction. Unfortunately, CpRu-sulfoxide complexes were shown to be inefficient and poorly selective catalysts for the enyne cycloisomerization and redox isomerization/C-H insertion reactions. We hypothesized that either the bound sulfoxide ligand was too electron-rich or that the catalyst had an insufficient number of coordination sites available for catalysis. In order to test our hypothesis, we synthesized CpRu complexes that contained more electron-withdrawing S-chiral ligands. While chiral sulfimide- and sulfinamide-containing complexes could promote enyne cycloisomerization, these catalysts were poorly enantioselective. These results led us to believe that the ligands were too weakly ligated to the metal center and decomplexed under the reaction conditions. Novel coordinatively unsaturated chiral indenylruthenium complexes with a tethered chiral sulfoxide were designed and synthesized. Enantiomeric ratios of up to 75:25 for enyne cycloisomerization and 84:16 for enyne hydroxycyclization could be obtained using these catalysts. When applied to the asymmetric redox isomerization/C-H insertion reaction, chiral indenylruthenium complexes could promote this reaction in up to 90:10 e.r. The main disadvantage of using these tethered complexes is that they are not commercially available and must be made through multistep syntheses. We discovered that commercially available catalyst CpRu(MeCN)3PF6, when used in conjunction with a chiral phosphoramidite ligand, can perform an asymmetric interrupted metallo-ene reaction of (E)-allylic chlorides in excellent enantioselectivity. To our knowledge, this represents the first example of using CpRu-phosphoramidite complexes for a catalytic asymmetric transformation. The C1-symmetry and 3,3'-substitution on the BINOL-based phosphoramidite were key to the high levels of enantioinduction observed. Carbocyclic and heterocyclic 5- and 6-membered rings could be constructed in> 20:1 d.r. and up to 99:1 e.r. As a demonstration of the utility of this methodology, diastereoselective Friedel-Crafts reactions were performed on the chiral benzylic alcohol products that were observed to proceed with retention of configuration.
Author:
Publisher: Elsevier
ISBN: 0443140030
Category : Science
Languages : en
Pages : 268
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Book Description
Earth-Abundant Transition Metal Catalyzed Reactions, Volume 74 in the Advances in Catalysis series, highlights new advances in the field, with this new volume presenting interesting chapters. Each chapter is written by an international board of authors. Chapters in this new release include in Chiral Iron Complexes for Asymmetric Catalysis, Recent advances in Ni-catalyzed Functionalization of Strong C-O and C-H Bonds, Low-valent Molecular Cobalt Complexes for Reductive Chemistry, Iron-catalyzed group-transfer reactions with hypervalent iodine reagents, and Iron Porphyrins for Mediating Atom Efficient C-C Bond Formations.
Author: B. L. Shaw
Publisher: Elsevier
ISBN: 1483181715
Category : Science
Languages : en
Pages : 231
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Book Description
Organo-Transition Metal Compounds and Related Aspects of Homogeneous Catalysis covers compounds that possess carbon atoms bonded to metal and to other carbon atoms. The order in which the substances appear in the book is based on the number of carbon atoms it have. The first section is about the alkyl, aryl, ethynyl, acyl, and carbene complexes. The second section deals with olefin and chelating diolefin complexes and complexes formed from acetylene. The following section covers the p-allylic complexes. The structures, stability, and bonding of alkyl and aryl complexes are fully covered. The magnetic moments and electronic spectra are discussed in detail.The fourth section discusses the conjugated diolefinic complexes that contain butadiene or cyclobutadiene. The rest of the book focuses on cyclopentadienyls, arene complexes, tropylium complexes, and complexes formed from cyclo-octatetraene or azulene. The book will be a useful tool for chemists, chemical engineers, and students and researchers in the field of chemistry.
Author: A. Stephen K. Hashmi
Publisher: John Wiley & Sons
ISBN: 3527319522
Category : Science
Languages : en
Pages : 419
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Book Description
With its impressive features, gold has led to completely new reaction types in recent years, which in turn have strongly influenced both organic catalysis and material science. Other fields where a significant amount of new results has been obtained include nanotechnology, self assembly/supramolecular systems and biochemical/medicinal chemistry. As a result, gold is one of the hottest topics in catalysis at the moment, with an increasing amount of research being carried out in this field. While focusing on homogeneous catalysis, this monograph also covers the main applications in heterogeneous catalysis. Following a look at the gold-catalyzed addition of heteroatom nucleophiles to alkynes, it goes on to discuss gold-catalyzed additions to allenes and alkenes, gold-catalyzed benzannulations, cycloisomerization and rearrangement reactions, as well as oxidation and reduction reactions. The whole is finished off with a section on gold-catalyzed aldol and related reactions and the application of gold-catalyzed reactions to natural product synthesis. Of interest to synthetic chemists and inorganic chemists, as well as organic chemists working in homogeneous catalysis, physical and technical chemists.
