Helene Pellissier – författare

Chiral molecules are needed for the production of many pharmaceuticals and materials, and catalytic asymmetric synthesis provides a method for the preparation of such chiral products. For the synthesis of complex molecules, such as natural products and biologically active compounds, more than one catalytic reaction may be necessary and tandem catalysis refers to the combination of catalytic reactions into one synthesis. By combing catalysts it enables a more efficient, economical and selective one pot approach for complex molecule synthesis which could not be achieved through single specific catalytic systems. The challenge is finding the right catalyst which is compatible with other catalysts but also tolerates reagents, solvent and intermediates generated during the course of the reaction.

Enantioselective Multicatalysed Tandem Reactions provides an overview of recent developments in the area. The first part of the book covers asymmetric tandem reactions catalysed by multiple catalysts from the same discipline (organocatalysts, two metal and multienzyme-catalysed reactions). The second part looks at tandem reactions catalysed by multiple catalysts from different disciplines including reactions catalysed by a combination of metals and organocatalysts, reactions catalysed by a combination of metals and enzymes, and finally reactions catalysed by a combination of organocatalysts and enzymes.

The book will appeal to researchers and professionals in academic and industrial laboratories interested in catalysis, biocatalysis and organic synthesis of chiral compounds.

Due to the lower costs of nickel catalysts and the high abundance of nickel complexes, enantioselective nickel-mediated transformations have received a continuous and growing attention in recent years. This book demonstrates the diversity of chemistry catalysed by chiral nickel catalysts. Discussing several different enantioselective transformations, this book presents the impressive range of uses that have been found for novel and already known nickel chiral catalysts, from basic organic transformations to completely novel methodologies including fascinating one-pot domino and multicomponent reactions. This much-needed book is ideal for researchers and industrialists in organic chemistry, synthesis and medicinal chemistry.

With a foreword from leading organic chemist Professor Paul Wender, this book collects the major developments reported in the past thirty years in the field of enantioselective reactions promoted by chiral cobalt catalysts, illustrating the power of these green catalysts to provide all types of organic reactions from the basic to completely novel methodologies.

The search for new methodologies to prepare optically pure products is one of the most active areas of research in organic synthesis. Of the methods available for preparing chiral compounds, catalytic asymmetric synthesis has attracted the most attention. In particular, asymmetric transition-metal catalysis is a powerful tool for performing reactions in a highly enantioselective fashion. Efforts to develop new asymmetric transformations have previously focused on the use of rare metals such as titanium, palladium, iridium and gold. However, the ever-growing need for environmentally friendly catalytic processes has prompted chemists to focus on the more abundant and less toxic first-row transition metals, such as cobalt, to develop new catalytic systems.

The ability of cobalt catalysts to adopt unexpected reaction pathways has led to an impressive number of enantioselective cobalt-promoted transformations being developed over the past three decades. These have included the synthesis of many different types of products, often under relatively mild conditions and with remarkable enantioselectivities. This book is a useful reference resource for chemists, both academic and industrial, working in organic synthesis and interested in greener or more economical catalytic alternatives.

With a foreword from leading organic chemist Professor Paul Wender, this book collects the major developments reported in the past thirty years in the field of enantioselective reactions promoted by chiral cobalt catalysts, illustrating the power of these green catalysts to provide all types of organic reactions from the basic to completely novel methodologies.

The search for new methodologies to prepare optically pure products is one of the most active areas of research in organic synthesis. Of the methods available for preparing chiral compounds, catalytic asymmetric synthesis has attracted the most attention. In particular, asymmetric transition-metal catalysis is a powerful tool for performing reactions in a highly enantioselective fashion. Efforts to develop new asymmetric transformations have previously focused on the use of rare metals such as titanium, palladium, iridium and gold. However, the ever-growing need for environmentally friendly catalytic processes has prompted chemists to focus on the more abundant and less toxic first-row transition metals, such as cobalt, to develop new catalytic systems.

The ability of cobalt catalysts to adopt unexpected reaction pathways has led to an impressive number of enantioselective cobalt-promoted transformations being developed over the past three decades. These have included the synthesis of many different types of products, often under relatively mild conditions and with remarkable enantioselectivities. This book is a useful reference resource for chemists, both academic and industrial, working in organic synthesis and interested in greener or more economical catalytic alternatives.

In a classical kinetic resolution, two enantiomers of a racemate are transformed into chiral products at different rates with a maximum theoretical yield of 50%. However, the need to reduce costs and waste in synthesis have led to efforts to develop novel resolution procedures proceeding beyond this 50% limited yield. This has led to the evolution of classical kinetic resolution into dynamic kinetic resolution (DKR), allowing a quantitative yield of one of the enantiomers. DKR combines the resolution step of kinetic resolution with an in-situ racemization of the chirally-labile substrate. It is only in the last two decades that chiral green organocatalysts have been demonstrated to be capable of promoting DKRs considerably expanding the synthetic scope of the powerful concept of DKR.

Collecting all the developments in the field of DKR, this book shows that a wide variety of organocatalysts allow excellent levels of stereocontrol and yields in many types of transformations. It is a great resource for academics and industrialists interested in green enantioselective catalytic reactions.

In a classical kinetic resolution, two enantiomers of a racemate are transformed into chiral products at different rates with a maximum theoretical yield of 50%. However, the need to reduce costs and waste in synthesis have led to efforts to develop novel resolution procedures proceeding beyond this 50% limited yield. This has led to the evolution of classical kinetic resolution into dynamic kinetic resolution (DKR), allowing a quantitative yield of one of the enantiomers. DKR combines the resolution step of kinetic resolution with an in-situ racemization of the chirally-labile substrate. It is only in the last two decades that chiral green organocatalysts have been demonstrated to be capable of promoting DKRs considerably expanding the synthetic scope of the powerful concept of DKR.

Collecting all the developments in the field of DKR, this book shows that a wide variety of organocatalysts allow excellent levels of stereocontrol and yields in many types of transformations. It is a great resource for academics and industrialists interested in green enantioselective catalytic reactions.

The goal of this book is to show the high potential of chiral sulfur-containing ligands to promote numerous asymmetric catalytic transformations. The important number of reports appeared in the literature over the last 35 years often highlighted spectacular results in terms of efficiency and enantioselectivity, allowing access to many biologically important molecules, which clearly demonstrates that these ligands can now be recognised as real competitors to the more usual phosphorus- or nitrogen-containing ligands. A key point of reference for post-graduate students, researchers and academics.

The aim of this book is to cover the very recent developments in asymmetric organocatalysis, focussing on those published since the beginning of 2008. The last decade has witnessed an explosive growth in the field of asymmetric organocatalysis with an impressive amount of new catalysts, novel methodologies, and applications in numerous reaction types, such as nucleophilic substitutions, addition reactions, as well as cycloadditions, oxidations, reductions, kinetic resolutions, and miscellaneous reactions. This very diverse and intensely developing field is too wide to cover in a single review. The timeliness of the book together with the expected impact is excellent, since nowadays asymmetric organocatalysis is arguably the most intensively developed field in organic chemistry. The book is designed to meet the demands of a postgraduate textbook,containing case studies and Q&A sections, as well as a practical book filled with facts and data useful as a working tool for the practitioner. The book is divided into ten sections, dealing successively with nucleophilic additions to electron-deficient C=C double bonds, nucleophilic additions to C=O double bonds, nucleophilic additions to C=N double bonds, nucleophilic additions to unsaturated nitrogen, nucleophilic substitutions at aliphatic carbon, cycloaddition reactions, oxidations, reductions, kinetic resolutions and desymmetrisations, and miscellaneous reactions.

The last 15 years have witnessed significant developments in the efficiency and scope of the application of DKR. These now offer a serious alternative to conventional methods for asymmetric synthesis. Indeed, impressive examples using new enzymes and major progress in the DKR of racemates have taken place over the past few years. The powerful combination of enzymes and metals has also been the subject of spectacular development. In addition, a new type of DKR, involving organocatalysts, has recently appeared. Although asymmetric catalysis has undergone development during the last two decades, the most common industrial process used to obtain enantiomerically pure compounds is still via resolution of racemic mixtures. This is despite the major disadvantage that only a maximum of 50% product yield can be obtained. It is not surprising that DKR, which solves the problem of the limitation in yield, has attracted an increasing amount of interest from both the industrial and the academic perspective. This book provides an up-date on the principle methods employed to obtain dynamic kinetic resolution (DKR) by either enzymatic or non-enzymatic methods. It also illustrates the diversity of useful chiral products that can be obtained through this powerful concept. Divided into three sections, the book deals successively with non-enzymatic methods, enzymatic methods, and the use of transition metals and enzymes in tandem.

This book covers the latest developments in asymmetric domino reactions, focussing on those published in the last 6 years. These fascinating reactions have rapidly become one of the most current fields in organic chemistry, since they allow reaching easily high molecular complexity in an economically favourable way with advantages of savings in solvent, time, energy, and costs. Unsurprisingly, the high levels of efficiency and enantioselectivity generally reached in these reactions have been exploited for the production of a wide number of complex chiral molecules with dense stereochemistry and functionality, which are motifs present in biologically active compounds and natural products. The book is divided into three principal sections, dealing successively with asymmetric domino reactions based on the use of chiral auxiliaries, asymmetric domino reactions based on the use of chiral metal catalysts, and asymmetric domino reactions based on the use of chiral organocatalysts, covering the literature since the beginning of 2006.