Download or read book The Design of New Substrates and Ligands for Rhodium Catalyzed Asymmetric Hydrogenation written by Tian Sun and published by . This book was released on 2013 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asymmetric hydrogenation is a significant research field in modern catalytic organic synthesis. In the past 50 years, the design of catalysts and substrates has been widely studied. A great number of phosphorus ligands for asymmetric hydrogenation have been developed. Three generations of catalysts have been reported by a number of scientists. The asymmetric hydrogenation becomes more and more efficient and applicable. High enantioselectivities and activities have been achieved. The design of substrates also makes significant progresses. Many successful examples have been reported in asymmetric hydrogenation of olefins, ketones, and imines. In chapter one, the development of phosphorus ligands is reported. The characters of phosphorus ligands are discussed and compared. Examples of representative catalysts are listed. The asymmetric hydrogenation of different substrates is also summarized and discussed. In chapter two, asymmetric hydrogenation of Îł-dehydroamino ketones catalyzed by a rhodium-chiral phosphorus ligand complex (up to 99% ee, 1000 TON) is reported. This reaction represents an efficient approach to chiral Îł-amino ketones. The reduction of Îł-amino ketones catalyzed by Palladium on carbon (Pd/C) leads to amphetamine precursors with quantitative yield and no significant enantioselectivity loss. In chapter three, high enantioselectivities (up to 99% ee) have been observed for the catalytic asymmetric hydrogenation of the Îł-ketone enol acetates. DuanPhos has been proved to be the most effective ligand for this reaction. High yield and enantioselectivity of the asymmetric hydrogenation of the Îł-ketone enol acetates demonstrates a feasible synthetic route to important pharmaceutical building blocks: Îł-hydroxy ketones. In chapter four, a series of new chiral secondary phosphine oxide (SPO) ligands are reported. Compared with traditional bisphosphine ligands, the SPO ligands are air stable, and have shorter synthetic routes. However, poor to moderate results are obtained using the new chiral SPO ligands. The study of SPO ligands still has many unsolved problems. The potential applications and challenges of SPO ligands are also discussed in chapter four.
Download or read book Metal Catalyzed Asymmetric Hydrogenation Evolution and Prospect written by and published by Academic Press. This book was released on 2021-11-23 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal-Catalyzed Asymmetric Hydrogenation, Volume 68 in the Advances in Catalysis series, fills the gap between journal papers and textbooks across diverse areas of catalysis research. For more than 60 years, this series has recorded and presented the latest progress in the field of catalysis, giving the scientific community comprehensive and authoritative reviews. Chapters in this new release include Asymmetric hydrogenation of functionalized olefins, Asymmetric hydrogenation of unfunctionalized olefins or with poorly coordinative groups, Asymmetric hydrogenation of imines, Asymmetric hydrogenation of ketones, Asymmetric hydrogenation in industry, and Computational insights into metal-catalyzed asymmetric hydrogenation. This series is an invaluable and comprehensive resource for chemical engineers and chemists working in the field of catalysis in both academia and industry, with this release focusing on solid acids, surface acidity and heterogeneous acid catalysis. Contains authoritative reviews written by experts in the field Explores topics that reflect progress in the field, such as catalyst synthesis, catalyst characterization, catalytic chemistry, reaction engineering, computational chemistry and physics Provides insightful and critical articles that are fully edited to suit various backgrounds
Download or read book Field Hearing on the State of VA Care in Hawaii written by United States. Congress. Senate. Committee on Veterans' Affairs and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rhodium Catalysis written by Carmen Claver and published by Springer. This book was released on 2017-12-15 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Organometallic Chemistry presents critical overviews of research results in organometallic chemistry. As our understanding of organometallic structure, properties and mechanisms increases, new ways are opened for the design of organometallic compounds and reactions tailored to the needs of such diverse areas as organic synthesis, medical research, biology and materials science. Thus the scope of coverage includes a broad range of topics of pure and applied organometallic chemistry, where new breakthroughs are being achieved that are of significance to a larger scientific audience. The individual volumes of Topics in Organometallic Chemistry are thematic. Review articles are generally invited by the volume editors. All chapters from Topics in Organometallic Chemistry are published OnlineFirst with an individual DOI. In references, Topics in Organometallic Chemistry is abbrev iated as Top Organomet Chem and cited as a journal.
Download or read book The Synthesis and Application of Bulky S stereogenic and P Stereogenic Chiral Ligands written by Seán Doran and published by . This book was released on 2012 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: This doctoral thesis was focused on the design and synthesis of novel chiral ligands for application in asymmetric catalysis. One of the best examples of asymmetric catalysis is the asymmetric hydrogenation reaction for its atom economy, ease of access to both S and R enantiomers and almost ultimate enantiomeric excess obtainable in a multitude of substrates. There has been much investigation into this reaction and there has been a plethora of chiral ligands designed which catalyze this reaction in high enantiomeric excess using metals such as rhodium, iridium and ruthenium. The vast majority of these ligands are diphosphines with their chirality lying either on the backbone of the ligand or on the coordinating phosphorus atom itself. In the beginning of this work investigation was undertook to explore the possibility of successfully employing a new type of ligand class in the asymmetric hydrogenation reaction, namely the N-phosphino sulfinamide or PNSO ligands. PNSO ligands had been successfully applied to the asymmetric Pauson-Khand reaction in the Riera group yielding cyclopentenone Pauson-Khand adducts in high yield and very high enantioselectivity. The family of PNSO ligands prepared in the Riera group was attractive because apart from the high yields and enantioselectivities obtained from the reactions in which they were used, they proved to be easily prepared in short syntheses from commercially available starting materials. It was believed if they could be successfully applied in asymmetric hydrogenation for their ease of preparation they would be an attractive alternative to the diphosphine ligand class. Unfortunately the first two PNSO-Rh complexes successfully prepared provided low enantioselectivities and difficulties were encountered while trying to prepare further analogues. After some time trying to achieve PNSO-Rh complex analogues unsuccessfully the direction of the project was shifted away from the N-phosphino sulfinamide ligand class in asymmetric hydrogenation. The MaxPhos ligand had recently been developed in the group and had proven highly promising. A study was demanded of its substrate scope as applied in rhodium catalyzed asymmetric hydrogenation. Substrates already described in the literature were prepared and the asymmetric hydrogenation of them catalyzed by the MaxPhos-Rh precatalyst was performed and conditions to do so were optimized. Of seven substrates prepared the MaxPhos-Rh proved to hydrogenate five of those with high enantioselectivity. The TOF of the MaxPhos rhodium catalyst applied in the hydrogenation of the Z-MAC substrate was examined by monitoring the flux of hydrogen and was calculated at 0.065 s-1. MaxPhos complexes of cobalt and palladium were prepared to form part of the investigation into widening the reaction scope of the ligand. [(MaxPhos)Co2(CO)4(C2H2)] proved to catalyze the Pauson-Khand reaction of norbornadiene and 1-hexyne with 24 % yield and 28 %, a noteworthy enantiomeric excess for the catalytic asymmetric Pauson-Khand reaction. Chalcogenated derivatives of MaxPhos were prepared. The diselenide was used to explore the electronic nature of the ligand. The MaxPhos-rhodium carbonyl stretching was examined. MaxPhos-BH3 was used to prepare mono-chalcogenated MaxPhos derivatives. They were applied also in asymmetric hydrogenation once complexed to rhodium but enantiomeric excess of no more than 21 % was obtained in the hydrogenation of the substrate Z-MAC. The aminophosphine, a chiral building block and key intermediate in the preparation of the MaxPhos ligand, was used in the attempt to prepare bulky chiral amidine ligands and although two such species were prepared they proved inapplicable in asymmetric catalysis.
Download or read book Modern Rhodium Catalyzed Organic Reactions written by P. Andrew Evans and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rhodium has proven to be an extremely useful metal due to its ability to catalyze an array of synthetic transformations, with quite often-unique selectivity. Hydrogenation, C-H activation, allylic substitution, and numerous other reactions are catalyzed by this metal, which presumably accounts for the dramatic increase in the number of articles that have recently emerged on the topic. P. Andrew Evans, the editor of this much-needed book, has assembled an internationally renowned team to present the first comprehensive coverage of this important area. The book features contributions from leaders in the field of rhodium-catalyzed reactions, and thereby provides a detailed account of the most current developments, including: Rhodium-Catalyzed Asymmetric Hydrogenation (Zhang) Rhodium-Catalyzed Hydroborations and Related Reactions (Brown) Rhodium-Catalyzed Asymmetric Addition of Organometallic Reagents to Electron Deficient Olefins (Hayashi) Recent Advances in Rhodium(I)-Catalyzed Asymmetric Olefin Isomerization and Hydroacylation Reactions (Fu) Stereoselective Rhodium(I)-Catalyzed Hydroformylation and Silylformylation Reactions and Their Application to Organic Synthesis (Leighton) Carbon-Carbon Bond-Forming Reactions Starting from Rh-H or Rh-Si Species (Matsuda) Rhodium(I)-Catalyzed Cycloisomerization and Cyclotrimerization Reactions (Ojima) The Rhodium(I)-Catalyzed Alder-ene Reaction (Brummond) Rhodium-Catalyzed Nucleophilic Ring Cleaving Reactions of Allylic Ethers and Amines (Fagnou) Rhodium(I)-Catalyzed Allylic Substitution Reactions and their Applications to Target Directed Synthesis (Evans) Rhodium(I)-Catalyzed [2+2+1] and [4+1] Carbocyclization Reactions (Jeong) Rhodium(I)-Catalyzed [4+2] and [4+2+2] Carbocyclizations (Robinson) Rhodium(I)-Catalyzed [5+2], [6+2], and [5+2+1] Cycloadditions: New Reactions for Organic Synthesis (Wender) Rhodium(II)-Stabilized Carbenoids Containing both Donor and Acceptor Substituents (Davies) Chiral Dirhodium(II)Carboxamidates for Asymmetric Cyclopropanation and Carbon-Hydrogen Insertion Reactions (Doyle) Cyclopentane Construction by Rhodium(II)-Mediated Intramolecular C-H Insertion (Taber) Rhodium(II)-Catalyzed Oxidative Amination (DuBois) Rearrangement Processes of Oxonium and Ammonium Ylides Formed by Rhodium(II)-Catalyzed Carbene-Transfer (West) Rhodium(II)-Catalyzed 1,3-Dipolar Cycloaddition Reactions (Austin) "Modern Rhodium-Catalyzed Organic Reactions" is an essential reference text for researchers at all levels in the general area of organic chemistry. This book provides an invaluable overview of the most significant developments in this important area of research, and will no doubt be an essential text for researchers at academic institutions and professionals at pharmaceutical/agrochemical companies.
Download or read book Rhodium Catalysis in Organic Synthesis written by Ken Tanaka and published by John Wiley & Sons. This book was released on 2018-12-31 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential reference to the highly effective reactions applied to modern organic synthesis Rhodium complexes are one of the most important transition metals for organic synthesis due to their ability to catalyze a variety of useful transformations. Rhodium Catalysis in Organic Synthesis explores the most recent progress and new developments in the field of catalytic cyclization reactions using rhodium(I) complexes and catalytic carbon-hydrogen bond activation reactions using rhodium(II) and rhodium(III) complexes. Edited by a noted expert in the field with contributions from a panel of leading international scientists, Rhodium Catalysis in Organic Synthesis presents the essential information in one comprehensive volume. Designed to be an accessible resource, the book is arranged by different reaction types. All the chapters provide insight into each transformation and include information on the history, selectivity, scope, mechanism, and application. In addition, the chapters offer a summary and outlook of each transformation. This important resource: -Offers a comprehensive review of how rhodium complexes catalyze a variety of highly useful reactions for organic synthesis (e.g. coupling reactions, CH-bond functionalization, hydroformylation, cyclization reactions and others) -Includes information on the most recent developments that contain a range of new, efficient, elegant, reliable and useful reactions -Presents a volume edited by one of the international leading scientists working in the field today -Contains the information that can be applied by researchers in academia and also professionals in pharmaceutical, agrochemical and fine chemical companies Written for academics and synthetic chemists working with organometallics, Rhodium Catalysis in Organic Synthesis contains the most recent information available on the developments and applications in the field of catalytic cyclization reactions using rhodium complexes.
Download or read book Rhodium Catalyzed Hydroformylation written by Piet W.N.M. van Leeuwen and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade there have been numerous advances in the area of rhodium-catalyzed hydroformylation, such as highly selective catalysts of industrial importance, new insights into mechanisms of the reaction, very selective asymmetric catalysts, in situ characterization and application to organic synthesis. The views on hydroformylation which still prevail in the current textbooks have become obsolete in several respects. Therefore, it was felt timely to collect these advances in a book. The book contains a series of chapters discussing several rhodium systems arranged according to ligand type, including asymmetric ligands, a chapter on applications in organic chemistry, a chapter on modern processes and separations, and a chapter on catalyst preparation and laboratory techniques. This book concentrates on highlights, rather than a concise review mentioning all articles in just one line. The book aims at an audience of advanced students, experts in the field, and scientists from related fields. The didactic approach also makes it useful as a guide for an advanced course.
Download or read book Rhodium catalyzed Asymmetric Hydrogenation Using Phosphoramidite Ligands written by Michel van den Berg and published by . This book was released on 2006 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Homogeneous Hydrogenation written by P.A. Chaloner and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous hydrogenation is one of the most thoroughly studied fields of homogeneous catalysis. The results of these studies have proved to be most important for an understanding of the underlying principles of the activation of small molecules by transition metal complexes. During the past three decades homogeneous hydrogenation has found widespread application in organic chemistry, including the production of important pharmaceuticals, especially where a sophisticated degree of selectivity is required. This volume presents a general account of the main principles and applications of homogeneous hydrogenation by transition metal complexes. Special attention is devoted to the mechanisms by which these processes occur, and the role of the recently discovered complexes of molecular hydrogen is described. Sources of hydrogen, other than H2, are also considered (transfer hydrogenation). The latest achievements in highly stereoselective hydrogenations have made possible many new applications in organic synthesis. These applications are documented by giving details of the reduction of important unsaturated substrates (alkenes, alkynes, aldehydes and ketones, nitrocompounds, etc.). Hydrogenation in biphasic and phase transfer catalyzed systems is also described. Finally, a discussion of the biochemical routes of H2 activation highlights the similarities and differences in performing hydrogenation in both natural and synthetic systems. For researchers working in the fields of homogeneous catalysis, especially in areas such as pharmaceuticals, plastics and fine chemicals.
Download or read book Rhodium Catalysis in Organic Synthesis written by Ken Tanaka and published by John Wiley & Sons. This book was released on 2019-05-06 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential reference to the highly effective reactions applied to modern organic synthesis Rhodium complexes are one of the most important transition metals for organic synthesis due to their ability to catalyze a variety of useful transformations. Rhodium Catalysis in Organic Synthesis explores the most recent progress and new developments in the field of catalytic cyclization reactions using rhodium(I) complexes and catalytic carbon-hydrogen bond activation reactions using rhodium(II) and rhodium(III) complexes. Edited by a noted expert in the field with contributions from a panel of leading international scientists, Rhodium Catalysis in Organic Synthesis presents the essential information in one comprehensive volume. Designed to be an accessible resource, the book is arranged by different reaction types. All the chapters provide insight into each transformation and include information on the history, selectivity, scope, mechanism, and application. In addition, the chapters offer a summary and outlook of each transformation. This important resource: -Offers a comprehensive review of how rhodium complexes catalyze a variety of highly useful reactions for organic synthesis (e.g. coupling reactions, CH-bond functionalization, hydroformylation, cyclization reactions and others) -Includes information on the most recent developments that contain a range of new, efficient, elegant, reliable and useful reactions -Presents a volume edited by one of the international leading scientists working in the field today -Contains the information that can be applied by researchers in academia and also professionals in pharmaceutical, agrochemical and fine chemical companies Written for academics and synthetic chemists working with organometallics, Rhodium Catalysis in Organic Synthesis contains the most recent information available on the developments and applications in the field of catalytic cyclization reactions using rhodium complexes.
Download or read book Rhodium Catalysis in Enantioselective Hydrogenative Transformations written by Joan Ramon Lao Mulinari and published by . This book was released on 2017 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: La present tesi doctoral se centra en el disseny i síntesi de lligands modulars fosforats de tipus fosfina-fosfit, en la seva aplicació posterior al desenvolupament de nous sistemes catalítics eficients i enantioselectius per a diferents transformacions hidrogenatives mediades per complexes de rodi derivats d'aquests lligands i en l'estudi del seu ús en la preparació de productes òpticament actius amb interès biològic, farmacèutic i agroquímic. En primer lloc, es descriu una innovadora estratègia sintètica per a la síntesi de nous lligands fosfina-fosfit que contenen un grup P-estereogènic i una cadena d'un sol àtom de carboni entre les dos funcionalitats fosforades com a característiques estructurals particulars. Posteriorment a la seva preparació, es va estudiar la seva aplicabilitat a reaccions d'hidrogenació i hidroformilació asimètriques d'alquens mediades per complexes de rodi derivats de lligands P-OP, obtenint alts valors de regio- i enantio-selectivitat en els productes de reacció. Per altra banda, el treball també cobreix el desenvolupament i l'aplicació de noves aproximacions catalítiques per a la síntesi de sulfòxids enantioenriquits a través de resolucions cinètiques hidrogenatives mediades per complexes de rodi derivats de lligands fosfina-fosfit. Aquesta estratègia sintètica, que es caracteritza per donar a lloc a dos sulfòxids enantioenriquits en una única etapa sintètica, s'ha aplicat a un ampli ventall de sulfòxids racèmics insaturats, obtenint alts valors de enantioselectivitat en els productes de reacció. A més a més, l'aplicabilitat sintètica d'aquesta estratègia catalítica ha pogut ser demostrada preparant tres intermedis sintètics enantioenriquits de compostos biològicament actius. Finalment, en l'última part del treball, es descriu el desenvolupament d'una nova metodologia estereoselectiva basada en la desimetrització hidrogenativa de 1,4-diens aquirals i la seva aplicació posterior a la preparació d'un conjunt d'alcohols secundaris i terciaris altament enantioenriquits que poden ser considerats productes d'alt interès sintètic.
Download or read book Enantioselective Chemical Synthesis written by Elias J. Corey and published by Elsevier. This book was released on 2013-10-23 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by world-renowned and best-selling experts, Nobel Laureate E. J. Corey and Laszlo Kurti, Enantioselective Chemical Synthesis offers an authoritative and comprehensive overview of the field’s progress; the processes and tools for key formations; future development for complex, stereocontrolled (enantiomeric or diastereoisomeric) molecules; and valuable examples of multi-step syntheses. Utilizing a color-coded scheme to illustrate chemical transformations, Enantioselective Chemical Synthesis provides clear explanation and guidance through vital asymmetrical syntheses and insight into the next steps for the field. Researchers, professionals, and academics will benefit from this valuable, thorough, and unique resource. In Part I, the authors present clearly, comprehensively and concisely the most useful enantioselective processes available to synthetic chemists. Part II provides an extensive discussion of the most logical ways to apply these new enantioselective methods to the planning of syntheses of stereochemically complex molecules. This hitherto neglected area is essential for the advancement of enantioselective synthesis to a more rational and powerful level. Part III describes in detail many reaction sequences which have been used successfully for the construction of a wide variety of complex target molecules Clearly explains stereochemical synthesis in theory and practice Provides a handy tool box for scientists wishing to understand and apply chiral chemical synthesis Describes almost 50 real life examples of asymmetric synthesis in practice and examines how the chiral centers were introduced at key synthetic stages
Download or read book Chiral Ferrocenes in Asymmetric Catalysis written by Li-Xin Dai and published by John Wiley & Sons. This book was released on 2010-02-01 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book meets the long-felt need for a reference on ferrocenes with the focus on catalysis. It provides a thorough overview of the synthesis and characterization of different types of chiral ferrocene ligands, their application to various catalytic asymmetric reactions, and versatile chiral materials as well as drug intermediates synthesized from them. Written by the "who's who" of ferrocene catalysis, this is a guide to the design of new ferrocene ligands and synthesis of chiral synthetic intermediates, and will thus be useful for organic, catalytic and synthetic chemists working in academia, industrial research or process development.
Download or read book Homogeneous Catalysis written by Piet W.N.M. van Leeuwen and published by Springer Science & Business Media. This book was released on 2006-08-02 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: No available as softcover No other book available that gives insight into so many reactions of importance, while the field of homogeneous catalysis is becoming more and more important to organic chemists, industrial chemists, and academia. Gives real insight in the many new and old reactions of importance, based on the author's extensive experience in both teaching and industrial practice. Provide background to chemists trained in a different discipline and graduate and masters students who take catalysis as a main or secondary topic.
Download or read book Ruthenium in Organic Synthesis written by Shun-Ichi Murahashi and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this comprehensive book, one of the leading experts, Shun-Ichi Murahashi, presents all the important facets of modern synthetic chemistry using Ruthenium, ranging from hydrogenation to metathesis. In 14 contributions, written by an international authorship, readers will find all the information they need about this fascinating and extraordinary chemistry. The result is a high quality information source and a indispensable reading for everyone working in organometallic chemistry. From the contents: Introduction (S.-I. Murahashi) Hydrogenation and Transfer Hydrogenation (M. Kitamura and R. Noyori) Oxidations (S.-I. Murahashi and N. Komiya) Carbon-Carbon Bond Formations via Ruthenacycle Intermediates (K. Itoh) Carbon-Carbon Bond Formation via pi-Allylruthenium Intermediates (T. Mitsudo) Olefin Metathesis (R. H. Grubbs) Cyclopropanation (H. Nishiyama) Nucleophilic Addition to Alkynes and Reactions via Vinylidene Intermediates (P. Dixneuf) Reactions via C-H Activation (N. Chatani) Lewis Acid Reactions (E. P. Kundig) Reactions with CO and CO2 (T. Mitsudo) Isomerization of Organic Substrates Catalyzed by Ruthenium Complexes (H. Suzuki) Radical Reactions (H. Nagashima) Bond Cleavage Reactions (S. Komiya)
Download or read book Rhodium Catalyzed Asymmetric Ring Opening of Oxabicyclic Alkenes and Palladium Catalyzed Carbon Halogen Bond Forming Reactions written by Christine Le and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atom-economical addition reactions to unsaturated carbonâ carbon bonds represent a powerful class of transformations in organic chemistry, since a great deal of molecular complexity can be generated from simple starting materials. Highly regio- and stereoselective processes have been made possible through the use of transition metal catalysts, alongside specialized ancillary ligands and in combination with rational substrate design. One area of research in the Lautens group involves the transition metal catalyzed asymmetric ring opening (ARO) of strained alkenes, which provides access to enantioenriched carbocyclic frameworks. Although a variety of coupling partners have been applied in this transformation, the use of soft carbon nucleophiles remains limited in scope. The first chapter describes a rhodium(I)-catalyzed ARO of meso-oxabicyclic alkenes using silyl enol ethers and ketene acetals. In analogy to the Mukaiyama aldol reaction, a novel silyl migration occurs, enabling an in situ protection of the chiral alcohols obtained. Developing new reactivity from Heck-type carbopalladation processes represents another research interest in the Lautens group. Oxidative addition into a carbonâ halogen bond constitutes the first step of nearly all palladium(0)-catalyzed cross-couplings. Conversely, reductive elimination from palladium(II) to yield an organohalide product represents a rare and often thermodynamically unfavoured process. The next two chapters address challenges in the synthesis of vinyl halides using palladium(0) catalysis via the intramolecular carbohalogenation and chlorocarbamoylation of alkynes. During our investigations, we discovered that the steric bulk of both the substrate and the phosphine ligand play an important role in promoting the desired reactivity. Mechanistic insight has been gained through combined experimental and computational studies, which implicate a palladium-catalyzed stereoisomerization in both of these transformations. Under certain conditions, we demonstrate that highly stereoselective trans-additions to alkynes can be achieved, which illustrates that specific substrate/catalyst combinations can override the inherent cis-selectivity in carbometallations. In the fourth chapter, a formal palladium(II)-catalyzed alkyne chlorocarbamoylation reaction is presented, which provides access to medicinally relevant methylene oxindole scaffolds. In contrast to the analogous protocol using palladium(0) catalysts, the reaction is initiated by an alkyne chloropalladation step, followed by intramolecular cross-coupling with a carbamoyl chloride. Experimental and computational studies provide insight into the mechanism of this reaction.
