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.

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 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A range of bridged bicyclic ketones were then prepared in order to probe their application in magnesium amide-mediated asymmetric deprotonation reactions. Initial studies were performed using a simple oxabicyclic substrate and our C2-symmetric bisamide. Pleasingly, after a short period of optimisation, the enantioenriched silyl enol ether was obtained in unprecedented yield and enantioselectivity. Attention was then turned to the analogous thiabicyclic ketone substrate. When performing the asymmetric deprotonation of this novel substrate under the previously optimised conditions at -78 oC, an outstanding level of enantioselection was observed (99:1 er), and the silyl enol ether product was obtained in good yield. Having achieved such impressive results at -78 oC, the efficiency of the transformation at room temperature was probed. Pleasingly, the enantioenriched silyl enol ether was obtained in excellent enantioselectivity (94:6 er) and yield, without the requirement for subambient temperatures. This is in marked contrast to the results achieved using the corresponding lithium amide, which delivered the silyl enol ether with a lower level of enantioselectivity (93:7) at -78 oC. Impressive results could also be achieved when the analogous alkylmagnesium amide was applied to the desymmetrisation of the thiabicyclic substrate. Studies within the area of magnesium base chemistry have been extended to the enantioselective total synthesis of the bicyclic eicosanoid, (-)-mucosin. The synthetic strategy which has been devised involves a magnesium base-mediated enantioselective deprotonation as the key transformation. As such, the required meso-ketone substrate has been prepared efficiently using a series of simple synthetic transformations. With the mesoketone in hand, conversion to the racemic enol silane has been achieved by utilising carboncentred magnesium base chemistry. In addition, preparation of the required allylic bromide electrophile has been completed in a short number of synthetic steps using readily available starting materials, and the racemic enol silane and allylic bromide coupling partners were reacted to give the required -substituted ketone in moderate yield. Efforts were then focused on the development of an asymmetric method for the preparation of the enol silane intermediate, delivering the optically-enriched enol silane in high enantioselectivity using our C2-symmetric magnesium bisamide (93:7 er) or the C2-symmetric lithium amide (94:6 er) at - 78 oC.

Download or read book Advances in Asymmetric Synthesis written by and published by Elsevier. This book was released on 1995-03-01 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Asymmetric Synthesis

Download or read book Advances in Asymmetric Synthesis written by Bozzano G Luisa and published by Elsevier. This book was released on 1997-05-16 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Asymmetric Synthesis

Download or read book Amide Bond Activation written by Michal Szostak and published by MDPI. This book was released on 2019-07-12 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: The amide bond represents a privileged motif in chemistry. The recent years have witnessed an explosion of interest in the development of new chemical transformations of amides. These developments cover an impressive range of catalytic N–C bond activation in electrophilic, Lewis acid, radical, and nucleophilic reaction pathways, among other transformations. Equally relevant are structural and theoretical studies that provide the basis for chemoselective manipulation of amidic resonance. This monograph on amide bonds offers a broad survey of recent advances in activation of amides and addresses various approaches in the field.

Download or read book Methodologies in Amine Synthesis written by Alfredo Ricci and published by John Wiley & Sons. This book was released on 2021-04-26 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discover a comprehensive overview of efficient synthetic routes to an important compound class in organic and pharmaceutical chemistry Methodologies in Amine Synthesis: Challenges and Applications delivers powerful and state-of-the-art methods for the efficient preparation of amines. The text summarizes recent advances in the electrophilic amination reaction, hydroamination, C-H amination and newly developed photocatalytic approaches. The distinguished editor has included resources that discuss organocatalytic and enzymatic routes to the generation of amines under mild and environmentally friendly conditions. The book also highlights the relevance of the amino function in bioactive molecules, drugs, and smart materials, as well as the palladium-catalyzed aromatic amination reaction. It presents efficient and practical synthetic methods, highlights the opportunities and challenges associated with each, and discusses their possible applications in pharmaceutical chemistry and materials science. Edited by the expert who wrote Modern Amination Methods and Amino Group Chemistry, the book includes a breadth and depth of material essential to the practice of academic and industrial chemists working in organic synthesis and catalysis. Readers will also benefit from the inclusion of: A thorough introduction to new openings and perspectives in the electrophilic amination Discussions of asymmetric catalysed hydroaminomethylation and amino organocatalysis A treatment of the synthetic application of transaminase or MAO biocatalysis to the synthesis of amines An exploration of recent developments in C-H amination, as well as photocatalytic approaches to the synthesis of amines An examination of primary amines from renewable bio-based resources Perfect for organic, natural product, catalytic, medicinal, and polymer chemists, Methodologies in Amine Synthesis: Challenges and Applications will also earn a place in the libraries of materials scientists and chemists working with organometallics who desire a one-stop reference edited by a well-known expert in the field.

Download or read book Asymmetric Synthesis of Non Proteinogenic Amino Acids written by Ashot S. Saghyan and published by John Wiley & Sons. This book was released on 2016-11-14 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Authored by two internationally recognized experts with an excellent track record, this much-needed reference summarizes latest research in the rapidly developing field of stereoselective synthesis of enantiomerically enriched amino acids, particularly of non-proteinogenic origin. It highlights several different catalytic and stoichiometric asymmetric methods for their synthesis and also provides information on origin, biological properties, different synthetic strategies and important applications in medicine and pharmacology. Essential reading for synthetic chemists working in the field of asymmetric synthesis, natural products and peptide synthesis, stereochemistry, medicinal chemistry, biochemistry, pharmacology, and biotechnology.

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

Download or read book Principles and Applications of Asymmetric Synthesis written by Guo-Qiang Lin and published by John Wiley & Sons. This book was released on 2003-05-29 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Asymmetric synthesis remains a challenge to practicing scientistsas the need for enantiomerically pure or enriched compoundscontinues to increase. Over the last decade, a large amount ofliterature has been published in this field. Principles andApplications of Asymmetric Synthesis consolidates and evaluates themost useful methodologies into a one-volume resource for theconvenience of practicing scientists and students. Authored by internationally renowned scientists in the field, thisreliable reference covers more than 450 reactions and includesimportant stoichiometric as well as catalytic asymmetric reactions.The first chapter reviews the basic principles, commonnomenclature, and analytical methods, and the remainder of the bookis organized according to reaction type. The text examines suchtopics 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 othercyclizations Applications to the total synthesis of natural products Use of enzymes in asymmetric synthesis Practicing chemists in the pharmaceutical, fine chemical, andagricultural professions as well as graduate students will findthat Principles and Applications of Asymmetric Synthesis affordscomprehensive and current coverage.

Download or read book Isocyanide based Multicomponent Reactions written by Jonathan G. Rudick and published by Frontiers Media SA. This book was released on 2020-02-20 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

Download or read book Greene s Protective Groups in Organic Synthesis written by Peter G. M. Wuts and published by John Wiley & Sons. This book was released on 2012-12-20 with total page 1108 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fourth Edition of Greene's Protective Groups in Organic Synthesis continues to be an indispensable reference for controlling the reactivity of the most common functional groups during a synthetic sequence. This new edition incorporates the significant developments in the field since publication of the third edition in 1998, including... New protective groups such as the fluorous family and the uniquely removable 2-methoxybenzenesulfonyl group for the protection of amines New techniques for the formation and cleavage of existing protective groups, with examples to illustrate each new technique Expanded coverage of the unexpected side reactions that occur with protective groups New chart covering the selective deprotection of silyl ethers 3,100 new references from the professional literature The content is organized around the functional group to be protected, and ranges from the simplest to the most complex and highly specialized protective groups.

Download or read book Iron Catalysis written by Bernd Plietker and published by Springer Science & Business Media. This book was released on 2011-01-05 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: Juan I. Padrón and Víctor S. Martín: Catalysis by means of Fe-based Lewis acids; Hiroshi Nakazawa*, Masumi Itazaki: Fe–H Complexes in Catalysis; Kristin Schröder, Kathrin Junge, Bianca Bitterlich, and Matthias Beller: Fe-catalyzed Oxidation Reactions of Olefins, Alkanes and Alcohols: Involvement of Oxo- and Peroxo Complexes; Chi-Ming Che, Cong-Ying Zhou, Ella Lai-Ming Wong: Catalysis by Fe=X Complexes (X=NR, CR2); René Peters, Daniel F. Fischer and Sascha Jautze: Ferrocene and Half Sandwich Complexes as Catalysts with Iron Participation; Markus Jegelka, Bernd Plietker: Catalysis by Means of Complex Ferrates.

Download or read book Iron Catalysis in Organic Chemistry written by Bernd Plietker and published by John Wiley & Sons. This book was released on 2008-09-08 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first comprehensive book to cover this exciting field also deals with the biological aspects, such as enzymes with iron. Following an introduction, this handy reference and handbook goes on to deal with reductions, oxidations of C, H- and C=C bonds, oxidative allylic oxygenation and amination, the oxidation of heteroatoms, cross coupling reactions, aromatic and nucleophilic substitutions, addition to carbonyl compounds, and cyclisations as well as ring opening reactions. The chapters are clearly classified according to the reaction type, allowing readers to quickly locate the desired information.

Download or read book Organosulfur Chemistry in Asymmetric Synthesis written by Takeshi Toru and published by John Wiley & Sons. This book was released on 2008-09-08 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this first book to gather the information on this hot topic otherwise widely spread throughout the literature, experienced editors and top international authors cover everything the reader needs -- from the synthesis of chiral organosulfur compounds to applications and catalysis: * Asymmetric synthesis of chiral sulfinates and sulfoxides * Synthesis and use of chiral dithioacetal derivatives, ylids, chiral sulfoximines and sulfinamides * Use of chiral sulfoxides as ligands in catalysis * Asymmetric reactions of alpha-sulfenyl, alpha-sulfinyl and alpha-sulfonyl carbanions. As a result, readers will be able to improve their own performance in asymmetric synthesis.

Download or read book Asymmetric Phase Transfer Catalysis written by Keiji Maruoka and published by John Wiley & Sons. This book was released on 2008-09-08 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited by the leading expert on the topic, this is the first book to present the latest developments in this exciting field. Alongside the theoretical aspects, the top contributors provide practical protocols to give readers additional important information otherwise unavailable. A must for every synthetic chemist in academia and industry.

Download or read book Dienamine Catalysis for Organic Synthesis written by Kengadarane Anebouselvy and published by Royal Society of Chemistry. This book was released on 2018-03-02 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade a new era in asymmetric catalysis has been realised by the discovery of L-proline induced chiral enamines from carbonyls. Inspired by this, researchers have developed many other primary catalytic species in situ, more recently secondary catalytic species such as aminals have been identified for use in asymmetric synthesis. High-yielding asymmetric synthesis of bioactive and natural products through mild catalysis is an efficient approach in reaction engineering. In the early days, synthetic chemists mainly focused on the synthesis of complex molecules, with less attention on the reaction efficiency and eco-friendly conditions. Recent investigations have been directed towards the development of atom economy, eco-friendly and enantioselective synthesis for more targeted and efficient synthesis. Building on the momentum of this rapidly expanding research area, Dienamine catalysis for organic synthesis will provide a comprehensive introduction, from the preformed species, in situ generation and onto their applications in the synthesis of bioactive molecules and natural products.

Download or read book Hypervalent Iodine Chemistry written by Viktor V. Zhdankin and published by John Wiley & Sons. This book was released on 2013-10-01 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hypervalent Iodine Chemistry is the first comprehensive text covering all of the main aspects of the chemistry of organic and inorganic polyvalent iodine compounds, including applications in chemical research, medicine, and industry. Providing a comprehensive overview of the preparation, properties, and synthetic applications of this important class of reagents, the text is presented in the following way: The introductory chapter provides a historical background and describes the general classification of iodine compounds, nomenclature, hypervalent bonding, structural features, and the principles of reactivity of polyvalent iodine compounds. Chapter 2 gives a detailed description of the preparative methods and structural features of all known classes of organic and inorganic derivatives of polyvalent iodine. Chapter 3, the key chapter of the book, deals with the many applications of hypervalent iodine reagents in organic synthesis. Chapter 4 describes the most recent achievements in hypervalent iodine catalysis. Chapter 5 deals with recyclable polymer-supported and nonpolymeric hypervalent iodine reagents. Chapter 6 covers the "green" reactions of hypervalent iodine reagents under solvent-free conditions or in aqueous solutions. The final chapter provides an overview of the important practical applications of polyvalent iodine compounds in medicine and industry. This book is aimed at all chemists interested in iodine compounds, including academic and industrial researchers in inorganic, organic, physical, medicinal, and biological chemistry. It will be particularly useful to synthetic organic and inorganic chemists, including graduate and advanced undergraduate students. It comprehensively covers the green chemistry aspects of hypervalent iodine chemistry, making it especially useful for industrial chemists.