Download or read book New Methodologies for the Synthesis of Chiral Phosphorus Acids and Related Compounds written by Karen Winters (Chemist) and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organocatalysis has become a major subdiscipline in (asymmetric) organic synthesis. Among chiral organocatalysts, C2-symmetrical chiral phosphorus acids (CPAs) occupy a rather special place because they can catalyze numerous transformations as Brønsted acids, however, they suffer from serious limitations such as: extremely high cost (they are much too expensive for use on an industrial scale, and often too expensive even on much smaller academic scales), very high molecular weight, inability to access both enantiomers without a significant and separate synthetic effort, difficulty in catalyst-immobilization, etc. In order to solve these problems, which hamper the broader uses and applications of CPAs, our proposed approach is to rely on compounds in which the phosphorus atom is chiral (called P-stereogenic, P-chiral, or P-chirogenic) but the rest of the molecule is not. This dissertation presents our development and research findings for the synthesis of chiral phosphorus acids as well as their application in asymmetric organocatalysis.
Download or read book Synthesis of Carbon Phosphorus Bonds written by Robert Engel and published by CRC Press. This book was released on 2003-12-18 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthesis of Carbon-Phosphorus Bonds, Second Edition is a working guide for the laboratory, incorporating classical approaches with the recent developments of carbon-phosphorus (C-P) bond formation. These advances include the preparation of phosphoranes - specifically in the use of transient oxophosphoranes as intermediates in organophosphorus comp
Download or read book Synthesis and Reactivity of Some Co P Chiral Co III Complexes written by Lihui Sun and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chiral phosphorus compounds have attracted research interest due to their biological activity and potential applications. Asymmetric synthesis of chiral phosphorus compounds via transition-metal-mediated (TMM) chemistry, with its possibility to modify reaction conditions and to control stereochemistry of phosphorus through coordination, holds promise as a synthetic avenue for synthesis of new phosphorus materials. This thesis focuses on a novel method to synthesize chiral pentavalent phosphorus compounds via optical induction from transition metal complexes and examines the chemistry of the resulting inorganometallic phosphorus moieties for further transformations. -- Three series of Co-, P-chiral Co(III) complexes are synthesized via transition- metal-mediated (TMM) Arbuzov reactions. The structures and spectroscopic properties are described and the reactivity of the synthesized chiral phosphonate moieties are examined. Unlike their organic analogs, the inorganometallic phosphonates are inert to nucleophiles. Reaction with PCl5or SOCl2 under prolonged heating cleaves the Co-P bond. In the presence of BCI3, the perfluoro-substituted P- phosphito Co(III) complex reacts with the nucleophile to give a novel product, which involves C-F bond cleavage. -- The LUMOs of the inorganometallic phosphonates and their organic analogs are analysed at the Hückel level. The LUMOs of the inorganometallic phosphonates are metal-based while those of their organic analogs are dominated by the orbitals of phosphorus centre. The shift of the LUMO from phosphorus to metal explains the behavioural difference between organic and inorganometallic pentavalent phosphorus compounds.
Download or read book New Methodologies for the Preparation of Organophosphorus Compounds Via Carbon phosphorus Bond Formation written by Karla Bravo-Altamirano and published by . This book was released on 2007 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work developed in this dissertation consists in the development of new methodologies for the preparation of H-phosphinic acid derivatives and their P-chiral counterparts. Special emphasis is given to the role of H-phosphinates as useful synthons for organophosphorus compounds via tandem processes. A review of the most relevant literature in terms of the preparation methodologies and reactivity of H-phosphinic acid derivatives is provided in Chapter I. The following chapter describes the addition of hypophosphorous compounds to unsaturated substrates in presence of metal-catalysts. The mechanism, regioselectivity on alkynes, and reactivity of substituted alkenes, allenes, allenols, and 1,3-dienes as substrates in a palladium-catalyzed hydrophosphinylation was investigated. A novel alkyne hydrophosphinylation catalyzed by nickel chloride or its hydrate in the absence of added ligand was discovered and exploited in the synthesis of various important organophosphorus compounds. The third chapter details a tandem esterification---cross-coupling reaction of alkyl phosphinates with aryl, heteroaryl, alkenyl, and benzylic halides and triflates. Thus the reaction of the electrophilic substrate with a hypophosphorous acid salt, in the presence of a silicate, a base and the palladium catalyst provided directly a wide variety of H-phosphinates, which were not accessible previously. In the following chapter, transition metal-catalyzed reactions of hypophosphorous compounds with allylic electrophiles are disclosed. Allylic acetates, benzoates and carbonates undergo an effective cross-coupling in the presence of palladium catalysts where pure H-phosphinic acids can be isolated by a simple acidic work-up or esterified in situ to the corresponding H-phosphinate esters. Chapter V describes a palladium-catalyzed dehydrative allylation of hypophosphorous acid with allylic alcohols, in the absence of additives. The next chapter focuses on P-H bond activation of H-phosphinates through catalytic allylation and oxidation strategies, which lead to disubstituted phosphinic acid and phosphonic acids, respectively. In the last chapter, desymmetrization strategies to access P-chiral H-phosphinates are reported. Two different avenues are explored: the use of chiral ligands in palladium-catalyzed reactions and the use of chiral auxiliaries by means of esterification of hypophosphorous acid with chiral alcohols, where 8-phenylmenthol provides, in a palladium-catalyzed hydrophosphinylation reaction, our best result with around 70% diastereomeric excess.
Download or read book Chiral Sulfur Reagents written by Marian Mikolajczyk and published by CRC Press. This book was released on 1997-06-09 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last three decades, more than 40 different classes of chiral (mirror-image) sulfur compounds have been described, and a number of useful procedures and applications have been developed for their use. Emphasizing modern methodologies, Chiral Sulfur Reagents demonstrates the great potential of enantionmerically pure sulfur reagents in transmitting chirality to other centers. Each chapter highlights the synthesis and synthetic uses of a particular class of chiral sulfur reagent, followed by examples of the most important experimental procedures.
Download or read book Carbon phosphorus Bond Formation written by Yamina Belabassi and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this dissertation deals with the development of new methodologies for P-C bond formation as well as synthesizing biologically relevant organophosphorus compounds. A distinct emphasis is given to the important synthetic targets, the H-phosphinates. A review of relevant literature is provided in Chapter 1. Chapter 2 describes the synthesis and structural analyses, of triphenylmethyl-containing phosphorus compounds. For the first time, both phosphonothioic and boranophosphonic acids have been characterized by single X-ray diffractometry. The third chapter details the preparation and the reactivity of phosphine-borane complexes. Novel dialkoxyphosphine-borane complexes were introduced, both as general synthetic intermediates for the preparation of H-phosphinates or disubstituted phosphinic acids, and as boranophosphonate precursors. Related to this chemistry, silylation of an H-phosphinate intermediate can also be conducted and the resulting phosphonite protected with borane. This allows the temporary protection of the sensitive P-H group, so that manipulations of the alkyl chain might be conducted. In chapter 4, the palladium-catalyzed cross-coupling reaction of dialkylphosphites with aryl and heteroaryl halides is presented. An efficient, versatile and economically attractive alternative to the original Hirao cross-coupling by using only 1 mol% (or less) Pd(OAc)2/dppf is described. Moreover, first example of palladium-catalyzed P-C bond formation between activated aryl chlorides and a phosphite are herein reported. Chapter 5 focuses on the free-radical hydrophosphinylation of alkynes. The triethylborane-initiated radical addition of sodium hypophosphite to terminal alkyne affords the previously unknown 1,1-bis-H-phosphinates, precursors of the biologically relevant 1,1-bisphosphonates (e.g., treatment of bone diseases). Thus, the oxidative conversion of 1,1-bis-H-phosphinates to the corresponding bisphosphonates, as well as the synthesis of a series of bio-conjugates (steroids, carbohydrates, fluoroquinolones) was investigated. In the last chapter, the palladium-catalyzed hydrophosphinylation of hypophosphorous acid derivatives to terminal alkynes is reported. In an effort to improve the regioselectivity of the reaction, various terminal alkynes were tested, as well as the solvent and catalyst system.
Download or read book Science of Synthesis Houben Weyl Methods of Molecular Transformations Vol 42 written by Francois Mathey and published by Thieme. This book was released on 2014-05-14 with total page 2006 pages. Available in PDF, EPUB and Kindle. Book excerpt: Science of Synthesis: Houben-Weyl Methods of Molecular Transformations is the entirely new edition of the acclaimed reference series, Houben-Weyl, the standard synthetic chemistry resource since 1909. This new edition is published in English and will comprise 48 volumes published between the years 2000 and 2008. Science of Synthesis is a quality reference work developed by a highly esteemed editorial board to provide a comprehensive and critical selection of reliable organic and organometallic synthetic methods. This unique resource is designed to be the first point of reference when searching for a synthesis strategy. Contains the expertise of presently 400 leading chemists worldwide Critically evaluates the preparative applicability and significance of the synthetic methods Discusses relevant background information and provides detailed experimental procedures For full information on the Science of Synthesis series, visit the Science of Synthesis Homepage.
Download or read book Approaches to the Synthesis of Heterocyclic Phosphorus Compounds written by King Auyang and published by . This book was released on 1967 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book N Heterocyclic Carbenes in Organocatalysis written by Akkattu T. Biju and published by John Wiley & Sons. This book was released on 2019-01-07 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summarizing the emerging field of N-heterocyclic carbenes used in organocatalysis, this is an excellent overview of the synthesis and applications of NHCs focusing on carbon-carbon and carbon-heteroatom bond formation. Alongside comprehensive coverage of the synthesis, characteristics and applications, this handbook and ready reference also includes chapters on NHCs for polymerization reactions and natural product synthesis.
Download or read book Biomedical Index to PHS supported Research written by and published by . This book was released on 1987 with total page 1398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Asymmetric Synthesis in Organophosphorus Chemistry written by Oleg I. Kolodiazhnyi and published by John Wiley & Sons. This book was released on 2016-12-19 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Authored by one of the leading experts in the field, this is the only comprehensive overview of chiral organophosphorus compounds, from asymmetric synthesis to catalysis and pharmacological applications. As such, this unique reference covers the chemical background as well as spectroscopical analysis of phosphorus compounds, and thoroughly describes all the various synthetic strategies for these substances. Metal-, organo- and biocatalyzed reactions for the introduction of phosphorus are explained as are asymmetric oxidation and reduction methods for the preparation of all possible oxidation states of phosphorus. The text also includes industrial applications for these compounds. Of particular interest to chemists working in the field of asymmetric synthesis, as well as to the pharmaceutical industry due to the increasing number of phosphorous-containing drugs.
Download or read book Research Awards Index written by and published by . This book was released on 1989 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biomedical Index to PHS supported Research pt A Subject access A H written by and published by . This book was released on 1992 with total page 1064 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Artificial Metalloenzymes and MetalloDNAzymes in Catalysis written by Montserrat Diéguez and published by John Wiley & Sons. This book was released on 2018-02-21 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important reference for researchers in the field of metal-enzyme hybrid catalysis Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a comprehensive review of the most current strategies, developed over recent decades, for the design, synthesis, and optimization of these hybrid catalysts as well as material about their application. The contributors—noted experts in the field—present information on the preparation, characterization, and optimization of artificial metalloenzymes in a timely and authoritative manner. The authors present a thorough examination of this interesting new platform for catalysis that combines the excellent selective recognition/binding properties of enzymes with transition metal catalysts. The text includes information on the various applications of metal-enzyme hybrid catalysts for novel reactions, offers insights into the latest advances in the field, and contains an informative perspective on the future: Explores the development of artificial metalloenzymes, the modern and strongly evolving research field on the verge of industrial application Contains a comprehensive reference to the research area of metal-enzyme hybrid catalysis that has experienced tremendous growth in recent years Includes contributions from leading researchers in the field Shows how this new catalysis combines the selective recognition/binding properties of enzymes with transition metal catalysts Written for catalytic chemists, bioinorganic chemists, biochemists, and organic chemists, Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a unique reference to the fundamentals, concepts, applications, and the most recent developments for more efficient and sustainable synthesis.
Download or read book Asymmetric Functionalization of C H Bonds written by Shu-Li You and published by Royal Society of Chemistry. This book was released on 2015-08-13 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asymmetric C-H direct functionalization reactions are one of the most active and fascinating areas of research in organic chemistry due to their significance in the construction of molecular complexity without pre-activation, and the step economy and atom economy features in potential synthetic application. Distinguishing the reactivity among numerous C–H bonds in one single molecule represents one of the most challenging issues in organic synthesis and requires precise reaction design. As such, this field is now receiving increasing attention from researchers. This book provides the first comprehensive review of this field, summarizing the origin, mechanism, scope and applications of the asymmetric C-H bond functionalization reaction. It covers organocatalytic reactions and transition-metal-catalyzed reactions, as well as asymmetric C-H functionalization reactions not described in other books. Written by a leading expert in this field, the book is ideal for postgraduates and researchers working in organic synthesis, catalysis, and organometallic chemistry.
Download or read book Chiral Ferrocenes in Asymmetric Catalysis written by Li-Xin Dai and published by John Wiley & Sons. This book was released on 2010-02-01 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Handbook of Chiral Chemicals written by David Ager and published by CRC Press. This book was released on 2005-10-21 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: As pharmaceutical companies look to develop single enantiomers as drug candidates, chemists are increasingly faced with the problems associated with this subclass of organic synthesis. "The Handbook of Chiral Chemicals, Second Edition" highlights the problems associated with the production of chiral compounds on a commercial scale. The handbook fir
