Privileged Chiral Ligands And Catalysts
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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
Privileged Chiral Ligands In Asymmetric Catalysis
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Author : Tamio Hayashi
language : en
Publisher: Wiley-VCH
Release Date : 2010-03-01
Privileged Chiral Ligands In Asymmetric Catalysis written by Tamio Hayashi and has been published by Wiley-VCH this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-03-01 with Science categories.
Edited by one of the leading experts in the field, this handbook brings together the absolute top authors to cover every aspect of chiral ligands for asymmetric catalysis. As such, it closes a gap in the literature by summarizing the widely dispersed information on privileged ligands in one handy reference. Spanning everything from biphosphine to salen ligands, this is the ultimate "must-have" for every organic chemist in academia, as well as the pharmaceutical and agrochemical industry working in asymmetric catalysis.
Chiral Ligands
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Author : Montserrat Diéguez
language : en
Publisher: CRC Press
Release Date : 2021-05-13
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 2021-05-13 with Science 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 Sulfur Ligands
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Author : Hélène Pellissier
language : en
Publisher: Royal Society of Chemistry
Release Date : 2009
Chiral Sulfur Ligands written by Hélène Pellissier and has been published by Royal Society of Chemistry this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Science categories.
The goal of this book is to show the high potential of chiral sulfur-containing ligands to promote numerous asymmetric catalytic transformations. These ligands can now be recognised as real competitors to the more usual phosphorus- or nitrogen-containing ligands.
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.
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.
Design Synthesis And Evaluation Of Chiral Nonracemic Ligands And Catalysts For Asymmetric Synthesis
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Author : Michael P. A. Lyle
language : en
Publisher:
Release Date : 2005
Design Synthesis And Evaluation Of Chiral Nonracemic Ligands And Catalysts For Asymmetric Synthesis written by Michael P. A. Lyle and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Asymmetric synthesis categories.
The work described in this thesis concerns the design, synthesis and evaluation of new chiral nonracemic ligands and catalysts for use in asymmetric reactions. A series of chiral nonracemic chloroacetals were prepared from 2-chloro-4- methyl-6,7-dihydro-5H-[l]pyrindine-7-one and a variety of C2-symmetric and chiral nonracemic 1,2-ethanediols (R = Me, i-Pr and Ph). These chloroacetals were further elaborated, in a modular fashion, to provide a series of chiral ligands and catalysts. A new class of C2-symmetric 2,2'-bipyridyl ligands were prepared in one step fiom the chloroacetals via a nickel(0)-mediated homo-coupling reaction. These ligands were then evaluated as chiral directors in copper@)-catalyzed asymmetric cyclopropanation reactions of styrene and diazoesters (up to 44% ee). A chiral pyridine N-oxide and a C2-symmetric 2,2'-bipyridyl N, N'-dioxide were also prepared by direct oxidation of the corresponding pyridine and the 2,2'-bipyridine, respectively. These chiral N-oxides were evaluated as chiral catalysts in desymmeterization reactions of cis-stilbene oxide (up to 20% ee). A series of pyridylphosphine ligands (P, N-ligands) were subsequently prepared in two steps from the chloroacetals via a Suzuki coupling reaction with orthofluorophenylboronic and on subsequent displacement of the fluoride with the potassium anion of diphenylphosphine. These ligands were then evaluated in palladium-catalyzed asymmetric allylic substitution reactions of racemic 3-acetoxy-l,3-diphenyl-1-propene with dimethyl malonate. Optimization of the reaction conditions resulted in the formation of the alkylated product in excellent yield (91%) and in high enantiomeric excess (90%). A related chiral nonracemic and C2-symmetric 2,2'-bipyridyl ligand was prepared from 2-chloro-4-methyl-5H-[llpyrindine. This pyrindine was prepared from a common intermediate that was used in the synthesis of the first generation of ligands. The chirality of this second generation ligand was installed by a Sharpless asymmetric dihydroxylation reaction (90% ee). The subsequently elaborated 2,2'-bipyridyl ligand (enriched to>99% ee) was then evaluated in copper(1)-catalyzed asymmetric cyclopropanation reactions of alkenes and diazoesters. In the case of the reaction of para-fluorostyrene and tert-butyl diazoacetate, the corresponding cyclopropane was formed in good diastereoselectivity (92:8) and in excellent enantioselectivity (99% ee). This ligand was also evaluated in copper(I1)-catalyzed asymmetric Friedel-Crafts alkylation reactions of various substituted indoles (up to 90% ee) and in copper(1)- catalyzed asymmetric allylic oxidation reactions of cyclic alkenes with tert-butyl peroxybenzoate (up to 9 1 % ee).
Development And Evaluation Of Chiral Catalysts For Asymmetric C C And C H Bond Forming Reactions
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Author : Christian Ebner
language : en
Publisher: Cuvillier Verlag
Release Date : 2012-03-05
Development And Evaluation Of Chiral Catalysts For Asymmetric C C And C H Bond Forming Reactions written by Christian Ebner and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-03-05 with Science categories.
This work was dedicated to the development and evaluation of new chiral catalysts for asymmetric C-C and C-H bond forming reactions. In the first part of the thesis an ESI-MS screening method is described, which allows the determination of a chiral catalyst´s selectivity in the palladium catalyzed asymmetric allylic alkylation by testing its racemic form. The value of this new method was demonstrated when different new aryl-PHOX-type ligands, which are not easily accessible in their enantiopure form, were evaluated. In the second part new PHOX-type ligands were tested in the iridium-catalyzed asymmetric hydrogenation of different unsaturated compounds. Although low activities and selectivities were found in most cases, one ligand showed promising results in the hydrogenation of allylic alcohols and imines. Furthermore air- and moisture-stable secondary phosphine oxide (SPO) containing bidentate ligands were tested in the palladium-catalyzed asymmetric allylic alkylation reaction. SPO,N-ligands bearing a PHOX type backbone were inactive in this transformation as they tend to form inactive palladium-bis-ligand complexes. SPO,P ligands however, were able to promote the desired reaction in a highly selective fashion although only low activities were found. During this work as well a new organo-catalyst, based on the structure of 2,3-dihydrobenzo[1,4]oxazine, was developed which allows for the asymmetric organo-catalyzed transfer-hydrogenation of α,β-unsaturated aldehydes. This catalyst was able to reduce for the first time β, β-diaryl acrylaldehydes with very good activities and high enantioselectivities. Moreover an ESI-MS based mechanistic study on the tripeptide catalyzed conjugate addition reaction of aldehydes to nitroolefins was carried out. By this all reaction intermediates postulated for an enamine mechanism have been detected. Furthermore the attack of the enamine onto the nitroolefin was found to be the selectivity determining step in this process. The last part of this work aimed for the asymmetric α -allylation of carbonyl compounds by a tandem-catalysis approach. An intensive screening of both the organo-catalyst and the palladium-ligand led to reaction conditions which allowed for the selective mono-allylation of ketones in high yields. The formation of a quaternary center by α -allylation of α -branched aldehydes was also achieved. However, only low enantiomeric excesses were obtained in this transformation for the different catalyst systems tested.
Chiral Diazaligands For Asymmetric Synthesis
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Author : Marc Lemaire
language : en
Publisher: Springer
Release Date : 2010-02-12
Chiral Diazaligands For Asymmetric Synthesis written by Marc Lemaire and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-02-12 with Science categories.
The use of phosphine derivatives has historically induced the tremendous development of catalysis (both non-asymmetric and asymmetric). Although the chemistry of amines is more documented, the use of nitrogen-containing ligands only appeared recently. Nevertheless, during the last ten years, the results describing chiral diamine preparations and their uses in asymmetric catalysis and synthesis are increasing faster than their phosphorus counterparts. The reader will find in this volume the most recent methods for the synthesis of chiral diamines as well as their applications in asymmetric catalysis of CC bond formation. Particular attention will be given to spartein and derivatives of such diamines. Recently, the particular properties and the chemistry of amines allowed to obtain catalysts easy to separate and recycle and new types of ligands such as diaminocarbenes, ureas and thioureas. Finally, the complexing properties of some diamines allowed the formation of complexes with chirality "at the metal " which is of major theoretical interest and presents numerous potential applications.
Axially Chiral Compounds
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Author : Bin Tan
language : en
Publisher: John Wiley & Sons
Release Date : 2021-11-22
Axially Chiral Compounds written by Bin Tan 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 2021-11-22 with Science categories.
Axially Chiral Compounds Explore this comprehensive and current volume summarizing the characteristics, synthesis, and applications of axial chirality Appearing widely in natural products, biologically active molecules, asymmetric chemistry, and material science, axially chiral motifs constitute the core backbones of the majority of chiral ligands and organocatalysts in asymmetric catalysis. In a new work of particular relevance to synthetic chemists, Axially Chiral Compounds: Asymmetric Synthesis and Applications delivers a clearly structured and authoritative volume covering the classification, characteristics, synthesis, and applications of axial chirality. A must read for every synthetic chemist practicing today, the book follows the development history, research status, and applications of axial chirality. An introductory chapter familiarizes the reader with foundational material before the distinguished authors describe the different classes and the synthesis of axial chiral compounds used in asymmetric synthesis. The book concludes with a focus on the applications of chiral ligands, chiral catalysts, and materials. Readers will also benefit from the inclusion of: A thorough introduction to asymmetric synthesis, including biaryls atropisomers, heterobiaryls atropisomers, and non-biaryls atropisomers Explorations of chiral allene, spiro skeletons, and natural products Practical discussions of asymmetric transformation, chiral ligands, and chiral catalysts An examination of miscellaneous applications of axially chiral compounds Perfect for organic chemists, chemists working with or on organometallics, catalytic chemists, and materials scientists, Axially Chiral Compounds: Asymmetric Synthesis and Applications will also earn a place in the libraries of natural products chemists who seek a one-stop reference for compounds exhibiting axial chirality.