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Showing 1 - 7 of 7 matches in All Departments
Chiral titanium complexes are low-cost, low-toxicity and high-efficiency catalysts. Impressive progress on enantioselective titanium-catalysed transformations has been achieved in the past seven years, with exciting new discoveries ranging from basic reactions to novel methodologies. Despite this, the field has not been substantially reviewed since 2008.This book contains up to date research and covers all types of enantioselective transformations using chiral titanium catalysts. It illustrates the economic, health, and environmental benefits of chiral titanium catalysts, showing the types of highly enantioselective reactions that they are able to induce are unlimited.Work presented here is aimed at researchers in organic and catalytic chemistry, and has been carefully curated to encourage future research possibilities.
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.
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 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.
Indole derivatives are the most common heterocycle compounds present in nature, for this reason, they have been referred to as 'privileged structures'. In fact, many approved drugs - and natural products - belong to this family. Among indole derivatives, oxindoles have a structural complexity, which have stimulated generations of synthetic chemists to design strategies for assembling these structures, and their enantioselective synthesis is still growing.This book proposes to describe the known enantioselective syntheses of oxindole derivatives. It is divided in six chapters each referring to a specific class of asymmetric oxindole derivatives. After the introduction, Chapter 2 describes all-carbon spirooxindoles; Chapter 3, open chain 3,3-dialkyloxindoles; Chapter 4, 3-substituted-3-aminooxindoles; Chapter 5, 3-substituted-3-hydroxyoxindoles; Chapter 6, 3-hetero-3-substituted oxindoles. It will be a useful tool for synthetic chemists, who assemble total synthesis of natural products, as well as for drug discovery chemists either in academic or in industry R&S laboratories.
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.
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.
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