Synthesis Of Novel Chiral Ligands For Catalytic Asymmetric Reactions
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Synthesis Of Novel Chiral Ligands For Catalytic Asymmetric Reactions
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Author :
language : en
Publisher:
Release Date : 2006
Synthesis Of Novel Chiral Ligands For Catalytic Asymmetric Reactions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Catalysis categories.
A series of N-salicyl-beta-aminoalcohol ligands had been synthesized by three component Mannich type reaction followed by ring opening of oxazolidine derivatives with hydroxylamine hydrochloride. The reactions provided a series of chiral N-salicyl-beta-aminoalcohol ligands in high yields (84-92%) without any racemization. These synthesized compounds were evaluated as ligands for catalytic asymmetric Strecker reactions. N-Benzhydrylaldimines derived from aromatic and aliphatic aldehydes reacted withTMSCN in the presence of 10 mol% of Ti-ligand complex to give the alpha-aminonitriles in excellent yields and in up to >98% ee. In addition, the catalyst loading was successfully reduced to 2.5 mol% which is very effective and extremely simple for large scale synthesis. The presence of 2-propanol is essential to ensure good conversion and reaction rate. The absolute configuration of all products derived from the (S)-ligand was confirmed to be S. Racemization of alpha-aminophenylacetonitriles is catalyzed by weak acids such as silica (SiO[subscript 2]) or even methanol. However, the racemization can be suppressed by addition of either a base such as triethylamine (NEt[subscript 3]) or strong acid such as hydrochloric acid (HCI). Importantly, optically active alpha-aminoacetonitriles can be easily converted to arylglycines by complete hydrolysis with minimal racemization. (>80% and >90% ee). A transition state model to explain the enantioselectivity of the reaction is proposed. The present chiral catalysts showed their catalytic ability in not only asymmetric strecker reaction but also asymmetric Pudovic reaction as well as asymmetric Michael addition.
Catalytic Asymmetric Synthesis
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Author : Takahiko Akiyama
language : en
Publisher: John Wiley & Sons
Release Date : 2022-06-15
Catalytic Asymmetric Synthesis written by Takahiko Akiyama and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-06-15 with Science categories.
Catalytic Asymmetric Synthesis Seminal text presenting detailed accounts of the most important catalytic asymmetric reactions known today This book covers the preparation of enantiomerically pure or enriched chemical compounds by use of chiral catalyst molecules. While reviewing the most important catalytic methods for asymmetric organic synthesis, this book highlights the most important and recent developments in catalytic asymmetric synthesis. Edited by two well-qualified experts, sample topics covered in the work include: Metal catalysis, organocatalysis, photoredox catalysis, enzyme catalysis C–H bond functionalization reactions Carbon–carbon bond formation reactions, carbon–halogen bond formation reactions, hydrogenations, polymerizations, flow reactions Axially chiral compounds Retaining the best of its predecessors but now thoroughly up to date with the important and recent developments in catalytic asymmetric synthesis, the 4th edition of Catalytic Asymmetric Synthesis serves as an excellent desktop reference and text for researchers and students, from upper-level undergraduates all the way to experienced professionals in industry or academia.
Chiral Bisoxazoline Ligands In Catalytic Asymmetric Allylic Oxidation
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Author : Davoud Asgari
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2009-09
Chiral Bisoxazoline Ligands In Catalytic Asymmetric Allylic Oxidation written by Davoud Asgari and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-09 with categories.
The Past three decades have witnessed a major development in asymmetric catalysis in organic synthesis. New and powerful catalysts have been designed and developed which exhibit levels of enantioselectivity previously considered beyond reach for non-enzymatic processes. Nitrogen-based transition metal ligands such as bisoxazoline ligands have emerged as an efficient class of ligands in an increasing number of asymmetric transformations including cyclopropanation, aziridination, Diels-Alder reaction, reduction, aldol reaction, ene reactions, allylic oxidation, and etc. This book reviews the synthesis and applications of bisoxazoline-metal complexes in a variety of asymmetric transformations and then describes the design and synthesis of a novel class of C2-symmetric biarylbisoxazoline ligands and their application in copper catalyzed asymmetric allylic oxidation of olefins. Potential applications for chiral cycloalkenols derived from allylic oxidation are great. A clear example is the conversion of (S)-cyclohexenyl benzoate to the key aldehyde-methyl ester intermediate for the synthesis of inflammation mediator leukotriene B4.
Catalytic Methods In Asymmetric Synthesis
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Author : Michelangelo Gruttadauria
language : en
Publisher: John Wiley & Sons
Release Date : 2011-09-27
Catalytic Methods In Asymmetric Synthesis written by Michelangelo Gruttadauria and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-09-27 with Science categories.
This book covers advances in the methods of catalytic asymmetric synthesis and their applications. Coverage moves from new materials and technologies to homogeneous metal-free catalysts and homogeneous metal catalysts. The applications of several methodologies for the synthesis of biologically active molecules are discussed. Part I addresses recent advances in new materials and technologies such as supported catalysts, supports, self-supported catalysts, chiral ionic liquids, supercritical fluids, flow reactors and microwaves related to asymmetric catalysis. Part II covers advances and milestones in organocatalytic, enzymatic and metal-based mediated asymmetric synthesis, including applications for the synthesis of biologically active molecules. Written by leading international experts, this book consists of 16 chapters with 2000 References and illustrations of 560 schemes and figures.
Chiral Ligands
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Author : Montserrat Diéguez
language : en
Publisher: CRC Press
Release Date : 2021-05-12
Chiral Ligands written by Montserrat Diéguez and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-05-12 with Medical categories.
Many new drugs on the market are chiral compounds, that is, they can exist in two non-superimposable mirror-image forms. Asymmetric catalysis encompasses a large variety of processes for obtaining such compounds. The performance of the catalyst in those processes largely depends on the ligand that makes up the catalyst. This book describes the most relevant ligand libraries for some key processes, including an overview of the state of art and the key mechanistic aspects that favor a high catalytic performance. Key Features: The book presents historical content from the time of discovery for each family of ligands. Provides a description of the synthetic route and the ligand library's application in various catalytic asymmetric reactions Suitable as supplementary reading for courses targeting the design, synthesis and application of chiral catalysts, asymmetric catalysis and sustainable production Edited by a distinguished scientist in the field, the book has a diverse audience including research groups in homogeneous catalysis, particularly asymmetric transformations
Chiral Ferrocenes In Asymmetric Catalysis
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Author : Li-Xin Dai
language : en
Publisher: John Wiley & Sons
Release Date : 2010-02-01
Chiral Ferrocenes In Asymmetric Catalysis written by Li-Xin Dai and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-02-01 with Science categories.
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.
The Synthesis And Application Of Bulky S Stereogenic And P Stereogenic Chiral Ligands
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Author : Seán Doran
language : en
Publisher:
Release Date : 2012
The Synthesis And Application Of Bulky S Stereogenic And P Stereogenic Chiral Ligands written by Seán Doran and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
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.
New Frontiers In Asymmetric Catalysis
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Author : Koichi Mikami
language : en
Publisher: John Wiley & Sons
Release Date : 2007-02-16
New Frontiers In Asymmetric Catalysis written by Koichi Mikami and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-02-16 with Science categories.
A compilation of recent advances and applications in asymmetric catalysis The field of asymmetric catalysis has grown rapidly and plays a key role in drug discovery and pharmaceuticals. New Frontiers in Asymmetric Catalysis gives readers a fundamental understanding of the concepts and applications of asymmetric catalysis reactions and discusses the latest developments and findings. With contributions from preeminent scientists in their respective fields, it covers: * "Rational" ligand design, which is critically dependent on the reaction type (reduction, oxidation, and C-C bond formation) * Recent findings on activation of C-H bonds, C-C bonds, and small molecules (C=O, HCN, RN=C, and CO2) and the latest developments on C-C bond reorganization, such as metathesis * Advances in "chirally economical" non-linear phenomena, racemic catalysis, and autocatalysis * Some of the recent discoveries that have led to a renaissance in the field of organocatalysis, including the development of chiral Brönstead acids and Lewis acidic metals bearing the conjugate base of the Brönstead acids as the ligands and the chiral bi-functional acid/base catalysts The book ends with a thought-provoking perspective on the future of asymmetric catalysis that addresses both the challenges and the unlimited potential in this burgeoning field. This is an authoritative, up-to-date reference for organic chemists in academia, government, and industries, including pharmaceuticals, biotech, fine chemicals, polymers, and agriculture. It is also an excellent textbook for graduate students studying advanced organic chemistry or chemical synthesis.
Privileged Chiral Ligands And Catalysts
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Author : Qi-Lin Zhou
language : en
Publisher: John Wiley & Sons
Release Date : 2011-02-10
Privileged Chiral Ligands And Catalysts written by Qi-Lin Zhou and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-02-10 with Technology & Engineering categories.
Catalytic asymmetric synthesis has been one of the most active research areas in chemistry (Nobel Prize in 2001). The development of efficient chiral catalysts plays a crucial role in asymmetric catalysis. Although many chiral ligands/catalysts have been developed in the past decades, the most efficient catalysts are derived from a few core structures, called "privileged chiral catalysts". This ultimate "must have" and long awaited reference for every chemist working in the field of asymmetric catalysis starts with the core structure of the catalysts, explaining why a certain ligand or catalyst is so successful. It describes in detail the history, the basic structural characteristics, and the applications of these "privileged catalysts". This novel presentation provides readers with a much deeper insight into the topic and makes it a must-have for organic chemists, catalytic chemists, chemists working with/on organometallics, chemists in industry, and libraries. From the contents: * BINAP * Bisphosphacycles - From DuPhos and BPE to a Diverse Set of Broadly Applied Ligands * Josiphos Ligands: From Discovery to Technical Applications * Chiral Spiro Ligands * Chiral Bisoxazoline Ligands * PHOX Ligands * Chiral Salen Complexes * BINOL * TADDOLate Ligands * Cinchona Alkaloids * Proline Derivatives
Principles And Applications Of Asymmetric Synthesis
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Author : Guo-Qiang Lin
language : en
Publisher: Wiley-Interscience
Release Date : 2003-05-29
Principles And Applications Of Asymmetric Synthesis written by Guo-Qiang Lin and has been published by Wiley-Interscience this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-05-29 with Science categories.
Asymmetric synthesis remains a challenge to practicing scientists as the need for enantiomerically pure or enriched compounds continues to increase. Over the last decade, a large amount of literature has been published in this field. Principles and Applications of Asymmetric Synthesis consolidates and evaluates the most useful methodologies into a one-volume resource for the convenience of practicing scientists and students. Authored by internationally renowned scientists in the field, this reliable reference covers more than 450 reactions and includes important stoichiometric as well as catalytic asymmetric reactions. The first chapter reviews the basic principles, common nomenclature, and analytical methods, and the remainder of the book is organized according to reaction type. The text examines such topics as: Carbon-carbon bond formations involving carbonyls, enamines, imines, and enolates Asymmetric C-O bond formations including epoxidation, dihydroxylation, and aminohydroxylation Asymmetric synthesis using the Diels-Alder reaction and other cyclizations Applications to the total synthesis of natural products Use of enzymes in asymmetric synthesis Practicing chemists in the pharmaceutical, fine chemical, and agricultural professions as well as graduate students will find that Principles and Applications of Asymmetric Synthesis affords comprehensive and current coverage.