Search results for ""Author Hélène Pellissier""

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.

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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.

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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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