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The Development And Application Of Chiral Magnesium Amides And New Addition Oxidation Processes
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Book Synopsis The Development and Application of Chiral Magnesium Amides and New Addition-oxidation Processes by : James John Crawford
Download or read book The Development and Application of Chiral Magnesium Amides and New Addition-oxidation Processes written by James John Crawford and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Extending Applications of Magnesium Amide Bases in Asymmetric Synthesis and a Mild and Selective N-debenzylation Method by : Natalie R. Monks
Download or read book Extending Applications of Magnesium Amide Bases in Asymmetric Synthesis and a Mild and Selective N-debenzylation Method written by Natalie R. Monks and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expansion of the application of readily available chiral magnesium-bisamides was the overall focus of the majority of this study. Comparing a structurally simple C2-symmetric magnesium bisamide and a chelating magnesium bisamide, a range of cyclobutanone substrates have been desymmetrised. Early studies employed the chlorotriethylsilane electrophile, however, efficiency of the processes with the chosen base system with cyclobutanone substrates was low. When the alternative electrophile, diphenylphosphoryl chloride, was utilised, however, a drastic improvement in both reactivity and selectivity was achieved. Optimisation of the reaction conditions with both a C2-symmetric magnesium bisamide and a chelating magnesium bisamide revealed selectivities of up to 99:1 er for the enantioenriched enol phosphate products. Furthermore, it was found that no additives are required within this novel base system and the deprotonation can be performed at a more elevated temperature of -40 °C whilst maintaining high selectivity. This efficient desymmetrisation was applied to a range of cyclobutanone substrates and seven novel enol phosphate products were formed in enantioselectivities between 76:24 and 99:1er, with the majority producing ratios greater than 89:11 er. Further application of a C2-symmetric magnesium bisamide was also sought by employing this base reagent within the synthetic route towards the natural product (+)-(S)-Sporochnol A. To this end, a scalable pathway towards a novel 4,4-disubstituted cyclohexanone was devised. The asymmetric deprotonation of this intermediate, utilising a C2-symmetric magnesium bisamide, subsequently embedded the all carbon quaternary stereocentre required within the natural product. Trapping the resulting chiral enolate with diphenylphosphoryl chloride furnished the desired enol phosphate in 88:12 er, which is an excellent level of enantioselectivity for a substrate of this type at a reaction temperature of -78 °C. Furthermore, the utility of the enol phosphate product was highlighted through a palladium-catalysed cross-coupling reaction with a Grignard reagent. Although completion of the synthesis of (+)-(S)-Sporochnol A was not achieved, the key asymmetric deprotonation and subsequent cross-coupling step were successful and high yielding. An additional study was the development of an improved method for the oxidation of secondary N-benzylamines. The application of DIAD as a means to oxidise secondary N-benzylamines, followed by a subsequent hydrolysis step has been employed to afford debenzylated free amines. This oxidation methodology has thus been applied to a range of amine substrates as an improved, mild, and selective method for benzyl deprotection. High yields of the free amines were obtained and the reaction proved to be tolerant of other functional groups and heteroatoms. Moreover, when an enantiopure secondary N-benzylamine was deprotected, the free primary amine remained optically pure, proving that these mild conditions do not interfere with other functionality within the molecule.
Book Synopsis The Development and Application of Magnesium Amide Bases in Asymmetric Synthesis by : Linsey S. Bennie
Download or read book The Development and Application of Magnesium Amide Bases in Asymmetric Synthesis written by Linsey S. Bennie and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Novel Chiral Heteroleptic Magnesium Amides for Use in Enentioselective Synthesis by : Emma Louise Carswell
Download or read book Novel Chiral Heteroleptic Magnesium Amides for Use in Enentioselective Synthesis written by Emma Louise Carswell and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Development and Application of Magnesium Base-mediated Transformations by : Tina Weber
Download or read book The Development and Application of Magnesium Base-mediated Transformations written by Tina Weber and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The exploration of magnesium bases has been the focus of this programme. Utilising the readily prepared Mes2Mg as a base reagent in a slight excess of 1.5 mol, efficient mediation of the Shapiro reaction has been achieved. A range of easily accessible aryl tosylhydrazones, bearing electron-neutral or -donating substituents, delivered excellent levels of selectivity in electrophilic quench, up to 97:3 (E:H), in conjunction with yields up to 90 % of the corresponding disubstituted alkenes. With only 1.05 equivalents of Weinreb amides as electrophiles, yields as high as 77% could be obtained. Efforts to utilise more demanding dialkyl tosylhydrazones were of limited success. Mechanistic investigations and attempts to trap key intermediates revealed a substantial lack of reactivity of the carbon-centred base at ambient temperatures and below. Further utilisation of the in situ generated vinyl magnesium species within Kumada-type cross-coupling reactions was also briefly explored. Preliminary studies, employing iron(III) chloride as a catalyst and TMEDA as an additive, delivered up to 32% yield of the desired alkylated product. Initial investigations into the efficacy of Mes2Mg in Wittig reactions were focused on the formation of a non-stabilised phosphonium ylide and subsequent reaction with acetophenone. These studies furnished an unusually high E-selectivity of 4:1 (E:Z), albeit in low yields of the alkene product. The conversion of phosphonium salts bearing electron-withdrawing groups delivered yields of up to 93%. Extension of the methodology studies utilising magnesium base reagents within the synthesis of the natural product (-)-mucosin was targeted. Efficient preparation of two main fragments, the bicyclic core and the allylic side chain, furnished the desired compounds in 51 % and 41 % yield, respectively. In the key step, enantioselective deprotonation of the meso-ketone using a chiral magnesium bisamide produced the enol silane in excellent 92:8 selectivity and up to 87% yield. Reaction of the silylenol ether with the allylic bromide delivered the desired keto ester in a 70 % yield. As an alternative for the alkylation step, utilisation of Tsuji-Trost allylation chemistry was explored. Completion of the natural product focused at first on the reduction of the ketone moiety and subsequent installation of a bromide leaving group. Extensive 1H-NMR studies on the alcohol intermediate validated the proposed route towards (-)mucosin. Introduction of the final nbutyl side chain was attempted using a range of stoichiometric and catalytic organocuprate-based protocols. A second strategy towards (-)mucosin was devised, concentrating on alkylation of the ketone moiety instead of hydride reduction. However, the hindered position within the molecule prevented the nbutyl group introduction and the completion of the natural product in both routes.
Book Synopsis Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards by :
Download or read book Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards written by and published by . This book was released on 2006 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Alkaline-Earth Metal Compounds by : Sjoerd Harder
Download or read book Alkaline-Earth Metal Compounds written by Sjoerd Harder and published by Springer. This book was released on 2013-07-20 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Organometallic Chemistry presents critical overviews of research results in organometallic chemistry. As our understanding of organometallic structure, properties and mechanisms increases, new ways are opened for the design of organometallic compounds and reactions tailored to the needs of such diverse areas as organic synthesis, medical research, biology and materials science. Thus the scope of coverage includes a broad range of topics in pure and applied organometallic chemistry, where new breakthroughs are being achieved that are of significance to a larger scientific audience. The individual volumes of Topics in Organometallic Chemistry are thematic. Review articles are generally invited by the volume editors.
Book Synopsis Directory of Graduate Research by : American Chemical Society. Committee on Professional Training
Download or read book Directory of Graduate Research written by American Chemical Society. Committee on Professional Training and published by . This book was released on 2005 with total page 1932 pages. Available in PDF, EPUB and Kindle. Book excerpt: Faculties, publications and doctoral theses in departments or divisions of chemistry, chemical engineering, biochemistry and pharmaceutical and/or medicinal chemistry at universities in the United States and Canada.
Book Synopsis Handbook of Chiral Chemicals by : David Ager
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
Book Synopsis Chiral Reagents for Asymmetric Synthesis by : Leo A. Paquette
Download or read book Chiral Reagents for Asymmetric Synthesis written by Leo A. Paquette and published by John Wiley & Sons. This book was released on 2003-08-01 with total page 618 pages. Available in PDF, EPUB and Kindle. Book excerpt: Derived from the renowned, Encyclopedia of Reagents for Organic Synthesis (EROS), the related editors have created a new handbook which focuses on chiral reagents used in asymmetric synthesis and is designed for the chemist at the bench. This new handbook follows the same format as the Encyclopedia, including an introduction and an alphabetical arrangement of the reagents. As chiral reagents are the key for the successful asymmetric synthesis, choosing the right reagents is essential, in this handy reference the editors give details on how to prepare, store and use the reagents as well as providing key reactions to demonstrate where reagents have been successfully used. Comprehensive information on 226 reagents Covers 64 reagents which were not included in EROS All information in one easy to use volume – at an affordable price All reagents included will be added to e-EROS – please visit the site where you can gain access to over 50,000 reactions and 3,800 of the most frequently consulted reagents. Visit: www.interscience.wiley.com/eros
Book Synopsis Sustainable Chemistry by : Michael North
Download or read book Sustainable Chemistry written by Michael North and published by Royal Society of Chemistry. This book was released on 2016 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focussing on catalysis through non-endangered metals, this book is an important reference for researchers working in catalysis and green chemistry.
Book Synopsis Catalysis in Asymmetric Synthesis by : Vittorio Caprio
Download or read book Catalysis in Asymmetric Synthesis written by Vittorio Caprio and published by John Wiley & Sons. This book was released on 2009-03-09 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asymmetric synthesis has become a major aspect of modern organic chemistry. The stereochemical properties of an organic compound are often essential to its bioactivity, and the need for stereochemically pure pharmaceutical products is a key example of the importance of stereochemical control in organic synthesis. However, achieving high levels of stereoselectivity in the synthesis of complex natural products represents a considerable intellectual and practical challenge for chemists. Written from a synthetic organic chemistry perspective, this text provides a practical overview of the field, illustrating a wide range of transformations that can be achieved. The book captures the latest advances in asymmetric catalysis with emphasis placed on non-enzymatic methods. Topics covered include: Reduction of alkenes, ketones and imines Nucleophilic addition to carbonyl compounds Catalytic carbon-carbon bond forming reactions Catalytic reactions involving metal carbenoids Conjugate addition reactions Catalysis in Asymmetric Synthesis bridges the gap between undergraduate and advanced level textbooks and provides a convenient point of entry to the primary literature for the experienced synthetic organic chemist.
Book Synopsis Side Reactions in Organic Synthesis by : Florencio Zaragoza Dörwald
Download or read book Side Reactions in Organic Synthesis written by Florencio Zaragoza Dörwald and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most syntheses in the chemical research laboratory fail and usually require several attempts before proceeding satisfactorily. Failed syntheses are not only discouraging and frustrating, but also cost a lot of time and money. Many failures may, however, be avoided by understanding the structure-reactivity relationship of organic compounds. This textbook highlights the competing processes and limitations of the most important reactions used in organic synthesis. By allowing chemists to quickly recognize potential problems this book will help to improve their efficiency and success-rate. A must for every graduate student but also for every chemist in industry and academia. Contents: 1 Organic Synthesis: General Remarks 2 Stereoelectronic Effects and Reactivity 3 The Stability of Organic Compounds 4 Aliphatic Nucleophilic Substitutions: Problematic Electrophiles 5 The Alkylation of Carbanions 6 The Alkylation of Heteroatoms 7 The Acylation of Heteroatoms 8 Palladium-Catalyzed C-C Bond Formation 9 Cyclizations 10 Monofunctionalization of Symmetric Difunctional Substrates
Book Synopsis New Frontiers in Organoselenium Compounds by : Eder João Lenardão
Download or read book New Frontiers in Organoselenium Compounds written by Eder João Lenardão and published by Springer. This book was released on 2018-06-29 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent advances in and perspectives on the use of organoselenium compounds, primarily highlighting the new frontiers in the field of Green Chemistry, their therapeutic and biological relevance and new materials. Throughout its 200 pages, readers will find an updated and comprehensive review of new aspects of organoselenium chemistry and biochemistry. Fully referenced and written in an easy to read style, it offers readers a primary resource for including organoselenium derivatives in their projects. This book will be of interest to specialists, students and researchers involved in a broad range of fields, from synthetic green chemistry to medicinal chemistry and the chemistry of natural products. The connection between organoselenium compounds and green chemistry, despite having only recently emerged, is one of the subjects of this book. The first chapter highlights the use of Se-containing molecules as reagents and catalysts in new green protocols to access important organic transformations. The book provides a wealth of examples of bioactive Se-containing molecules, especially focusing on those with potential therapeutic uses. The second chapter focuses on the state of the art concerning the role of organoselenium compounds as antioxidants, GPx mimics, and derivatives endowed with different bioactive properties. “Organoselenium in nature” is the title of the third chapter, which equips readers with essential information on the main natural organoselenium compounds and where they are found. Selected aspects of the metabolism of selenium in plants and microorganisms are also discussed. In closing, the book includes a chapter dedicated to recent advances concerning the nonbonding interactions between organochalcogen compounds. This is currently a hot topic in selenium chemistry and biochemistry, and here readers will find key insights into the chalcogen bond and its role in the biological activity of organoselenium compounds.
Book Synopsis Handbook for Chemical Process Research and Development by : Wenyi Zhao
Download or read book Handbook for Chemical Process Research and Development written by Wenyi Zhao and published by CRC Press. This book was released on 2016-11-03 with total page 864 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook for Chemical Process Research and Development focuses on developing processes for chemical and pharmaceutical industries. Forty years ago there were few process research and development activities in the pharmaceutical industry, partially due to the simplicity of the drug molecules. However, with the increasing structural complexity, especially the introduction of chiral centers into the drug molecules and strict regulations set by the EMA and FDA, process R&D has become one of the critical departments for pharmaceutical companies. This book assists with the key responsibility of process chemists to develop chemical processes for manufacturing pharmaceutical intermediates and final drug substances for clinical studies and commercial production.
Book Synopsis Early Main Group Metal Catalysis by : Sjoerd Harder
Download or read book Early Main Group Metal Catalysis written by Sjoerd Harder and published by John Wiley & Sons. This book was released on 2020-04-06 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early Main Group Metal Catalysis gives a comprehensive overview of catalytic reactions in the presence of group 1 and group 2 metals. Chapters are ordered to reaction type, contain educational elements and deal with concepts illustrated by examples that cover the main developments. After a short introduction on polar organometallic chemistry and synthesis of early main group metal complexes, a variety of catalytic reactions are described, e.g. polymerization of alkenes, hydroamination and phosphination reactions, hydrosilylation, hydroboration and hydrogenation catalysis, as well as enantioselective and Lewis-acid catalysis. The book addresses organic chemists and researchers in industry interested in the state-of-the-art and new possibilities of early main group metal catalysis as well as newcomers to the field. Written by a team of leaders in the field, it is a very welcome addition to the area of main group metal chemistry, and to the field of catalysis.
Book Synopsis Asymmetric Dearomatization Reactions by : Shu-Li You
Download or read book Asymmetric Dearomatization Reactions written by Shu-Li You and published by John Wiley & Sons. This book was released on 2016-09-13 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first comprehensive account of the rapidly growing field of asymmetric dearomatization reactions with a focus on catalytic methods. It introduces the concept of dearomatization and describes recent progress in asymmetric reaction procedures with different catalyst systems, such as organocatalysts, transition metal catalysts, and enzymes. Chapters on dearomatizations of electron-deficient aromatic rings, dearomatization reactions via transition metal-catalyzed cross-couplings as well as dearomatization strategies in the synthesis of complex natural products are also included. Written by pioneers in the field, this is a highly valuable source of information not only for professional synthetic chemists in academia and industry but also for all those are interested in asymmetric methodologies and organic synthesis in general.
