P-Chiral Phosphorus Ligands: Synthesis and Application in Asymmetric Hydrogenation PDF Download

Author: Björn Gschwend
Publisher: Cuvillier Verlag
ISBN: 3736931530
Category : Science
Languages : de
Pages : 292

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Author: Armin Börner
Publisher:
ISBN:
Category : Asymmetric synthesis
Languages : en
Pages : 512

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Author: Paul C. J. Kamer
Publisher: John Wiley & Sons
ISBN: 1118299701
Category : Technology & Engineering
Languages : en
Pages : 673

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Book Description
Over the last 60 years the increasing knowledge of transition metal chemistry has resulted in an enormous advance of homogeneous catalysis as an essential tool in both academic and industrial fields. Remarkably, phosphorus(III) donor ligands have played an important role in several of the acknowledged catalytic reactions. The positive effects of phosphine ligands in transition metal homogeneous catalysis have contributed largely to the evolution of the field into an indispensable tool in organic synthesis and the industrial production of chemicals. This book aims to address the design and synthesis of a comprehensive compilation of P(III) ligands for homogeneous catalysis. It not only focuses on the well-known traditional ligands that have been explored by catalysis researchers, but also includes promising ligand types that have traditionally been ignored mainly because of their challenging synthesis. Topics covered include ligand effects in homogeneous catalysis and rational catalyst design, P-stereogenic ligands, calixarenes, supramolecular approaches, solid phase synthesis, biological approaches, and solubility and separation. Ligand families covered in this book include phosphine, diphosphine, phosphite, diphosphite, phosphoramidite, phosphonite, phosphinite, phosphole, phosphinine, phosphinidenene, phosphaalkenes, phosphaalkynes, P-chiral ligands, and cage ligands. Each ligand class is accompanied by detailed and reliable synthetic procedures. Often the rate limiting step in the application of ligands in catalysis is the synthesis of the ligands themselves, which can often be very challenging and time consuming. This book will provide helpful advice as to the accessibility of ligands as well as their synthesis, thereby allowing researchers to make a more informed choice. Phosphorus(III) Ligands in Homogeneous Catalysis: Design and Synthesis is an essential overview of this important class of catalysts for academic and industrial researchers working in catalyst development, organometallic and synthetic chemistry.

Author: Antonio Belmiro Gil da Silva Fortes
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Seán Doran
Publisher:
ISBN:
Category :
Languages : en
Pages : 305

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Book Description
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.

Author: Kexuan Huang
Publisher:
ISBN:
Category : Ligands
Languages : en
Pages : 103

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Author: Li-Xin Dai
Publisher: John Wiley & Sons
ISBN: 3527322809
Category : Science
Languages : en
Pages : 433

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Book Description
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.

Author: Tsuneo Imamoto
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 184

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Book Description
Organic synthesis with lanthanides has experienced enormous growth in the last ten years. Numerous synthetic reactions have been explored by the use of lanthanide reagents, and some of these have become indispensablein modern organic synthesis. This book describes the remarkable scope and potential of these reagents, addressing this rapidly growing area from a practical point-of-view. The author has summarized synthetically useful and novel organic transformations, emphasizing the characteristic properties of lanthanide reagents. These transformations are concisely and skillfully presented in many schemes and tables, with actual illustrative preparations. The coverage includes the use of lanthanide metals, the powerful divalent reagents such as samarium (II) iodide, the key trivalent reagents and their particular role as catalysts in selective reductions and cycloadditions, and the tetravalent lanthanides as oxidants. Describes the remarkable scope and potential of lanthanide reagents from a practical point-of-view Presents actual experimental procedures Provides a concise presentation of useful and novel organic transformations in table format

Author: Patrick J. Walsh
Publisher: University Science Books
ISBN: 9781891389542
Category : Science
Languages : en
Pages : 692

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Book Description
This work describes the essential aspects of enantioselective catalysis, with chapters organised by concept rather than by reaction type. Each concept is supported by examples to give the reader broad exposure to a wide range of catalysts, reactions and reaction mechanisms.

Author: Soumyadeep Chakrabortty
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
This PhD thesis introduced a new chiral phosphorus ligand library and their application in Rh-catalyzed asymmetric hydrogenation of functionalized olefins. A cobalt-based catalyst has been developed for the synthesis of chiral cyclic amides via enantioselective hydrogenation employing a commercially available bisphosphine ligand. Chiral 5-methyl-pyrrolidinone was synthesized via Ru-catalyzed asymmetric reductive amination using levulinic acid as platform molecule.eng