Download or read book Novel Hydroxamic Acid Derived Ligands for Vanadium Catalysed Asymmetric Epoxidations written by Dominik Ohlmann and published by GRIN Verlag. This book was released on 2019-04-23 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research Paper (postgraduate) from the year 2007 in the subject Chemistry - Organic Chemistry, grade: 1,0, University of Glasgow (Chemistry), language: English, abstract: During this project, we reached the aim of establishing synthetic routes to new hydroxamic acid derivatives, which were used as ligands for asymmetric epoxidation of allylic alcohols in water. Three new ligands, (S, R)-3, (S, S)-3 and 14 were successfully synthesized and subsequently tested on standard substrates. To accomplish the ligand synthesis, we used known procedures as well as new ones, for example the coupling of in situ-protected hydroxylamine 5a and activated mixed anhydride 13. As yields were not always satisfying (see Experimental), optimization of several steps could be a general aim for future work, especially considering the synthesis up-scaling of promising ligand 14.
Download or read book Amino Acid derived Hydroxamic Acids as Ligands in Asymmetric Vanadium Catalysed Epoxidation written by Zaïnaba Bourhani and published by . This book was released on 2005 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design of New Bishydroxamic Acid Ligands for Vanadium catalyzed Asymmetric Epoxidation written by Wei Zhang and published by . This book was released on 2007 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: New chiral C2-symmetric bishydroxamic acid ligands were designed and successfully synthesized. They have been applied to the vanadium-catalyzed asymmetric epoxidation of allylic alcohols, as well as homoallylic alcohols, to provide excellent enantioselectivities. Also, they could be applied to the kinetic resolution of alcohols. The vanadium and bishydroxamic acid ligand catalyst system has been demonstrated to be highly efficient and convenient: (1) ligand design to achieve high enantioselectivities for Z-olefins, (2) less than 1 mol% catalyst loading, (3) reaction conditions at 0°C to room temperature for fewer hours, (4) use of aqueous TBHP (tert-butyl hydroperoxide) as an achiral oxidant instead of anhydrous TBHP, and (5) easy work-up procedure for small epoxy alcohols. Meanwhile, it has been demonstrated that the negative effect of dynamic ligand exchange of monohydroxamic acid ligands was not observed in the vanadium-bishydroxamic acid catalyst system.
Download or read book Vanadium catalyzed Asymmetric Epoxidations of Allylic Alcohols and Radical Cyclization fragmentation en Route to an Eight membered Ring written by Madison McCrea-Hendrick and published by . This book was released on 2011 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part one of this thesis describes the catalytic activity of Schiff base ligands and vanadium towards the asymmetric epoxidation of allylic alcohols. Currently, the ligands used for the vanadium-catalyzed epoxidation are hydroxamic acids. However, vanadium catalyzed reactions employing Schiff bases as ligands have been reported by various groups. We investigated these Schiff base ligands for enantioselectivity of epoxidation reactions. While Schiff bases are an alternative to the use of hydroxamic acids, enantioselectivity using the former was no greater than 10% ee. Part two of this thesis describes the efforts towards the synthesis of an eight-membered carbocycle through a radical mediated cyclization/fragmentation pathway. Previous methods for the construction of eight-membered rings include olefin metathesis and transition-metal catalyzed cycloadditions. Molander1 has also formed eight-membered rings through various radical cascade reactions initiated by SmI2. Our efforts towards an eight-membered ring using SmI2 concentrated on a vinyl cyclopropane as a radical trap were unsuccessful.
Download or read book Designing new chiral hydroxamic acid ligands for the asymmetric epoxidation reaction in water written by Louise E. Czemerys and published by . This book was released on 2009 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Herein, we report the synthesis of new chiral hydroxamic acid ligands for the V-catalysed asymmetric epoxidation reaction in aqueous solution. During the course of this project, a wide range of allylic alcohols were epoxidised under mild reaction conditions. The target epoxides were isolated in good-to-excellent yields with up to 94% ee. To further develop the project, we also report that the range of substrates has been extended to unfunctionalised alkenes. These materials have been successfully converted to the corresponding allylic alcohols in the presence of SeO2 and acetic acid. Asymmetric epoxidation was then achieved under anhydrous conditions in good-to-moderate yields with up to 76% ee and in certain cases, the overall transformation can occur as a one-pot process. A brief investigation into the development of organocatalytic transfer hydrogenation mediated by chiral pyridines has also been carried out. In this project, a range of chiral quarternary ammonium salts have been prepared as precursors to the corresponding dihydropyridines. It was our initial intention to utilise these chiral dihydropyridines in the enantioselective reduction of imines. This would result in the formation of the desired chiral amine and a quaternary pyridinium salt, which could then be reduced to reform the dihydropyridine in a catalytic cycle. However, with all pyridinium salts formed we were unable to produce the target dihydropyridines and this project was consequently abandoned.
Download or read book Applications of EPR and NMR Spectroscopy in Homogeneous Catalysis written by Evgenii Talsi and published by CRC Press. This book was released on 2017-04-07 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews advances in important and practically relevant homogeneous catalytic transformations, such as single-site olefin polymerizations and chemo- and stereo-selective oxidations. Close attention is paid to the experimental investigation of the active sites of catalytic oxidation systems and their mechanisms. Major subjects include the applications of NMR and EPR spectroscopic techniques and data obtained by other physical methods. The book addresses a broad readership and focus on widespread techniques available in labs with NMR and EPR spectrometers.
Download or read book Synthesis of Novel Chiral Ligands for Catalytic Asymmetric Reactions written by and published by . This book was released on 2006 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Modern Oxidation Methods written by Jan-Erling Bäckvall and published by John Wiley & Sons. This book was released on 2011-08-02 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: While rust is an unwanted oxidation reaction, there are also many other useful oxidation reactions that are extremely important and number among the most commonly used reactions in the chemical industry. This completely revised, updated second edition now includes additional sections on industrial oxidation and biochemical oxidation. Edited by one of the world leaders in the field, high-quality contributions cover every important aspect from classical to green chemistry methods: - Recent Developments in Metal-catalyzed Dihydroxylation of Alkenes - Transition Metal-Catalyzed Epoxidation of Alkenes - Organocatalytic Oxidation. Ketone-Catalyzed Asymmetric Epoxidation of Alkenes and Synthetic Applications - Catalytic Oxidations with Hydrogen Peroxide in Fluorinated Alcohol Solvents - Modern Oxidation of Alcohols using Environmentally Benign Oxidants - Aerobic Oxidations and Related Reactions Catalyzed by N-Hydro xyphthalimide - Ruthenium-Catalyzed Oxidation for Organic Synthesis - Selective Oxidation of Amines and Sulfides - Liquid Phase Oxidation Reactions Catalyzed by Polyoxometalates - Oxidation of Carbonyl Compounds - Manganese-Catalyzed Oxidation with Hydrogen Peroxide - Biooxidation with Cytochrome P450 Monooxygenases By providing an overview of this vast topic, the book represents an unparalleled aid for organic, catalytic and biochemists working in the field.
Download or read book Green Sustainable Process for Chemical and Environmental Engineering and Science written by Rajender Boddula and published by Elsevier. This book was released on 2021-03-18 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Green Sustainable Process for Chemical and Environmental Engineering and Science: Solid State Synthetic Methods cover recent advances made in the field of solid-state materials synthesis and its various applications. The book provides a brief introduction to the topic and the fundamental principles governing the various methods. Sustainable techniques and green processes development in solid-state chemistry are also highlighted. This book also provides a comprehensive literature on the industrial application using solid-state materials and solid-state devices. Overall, this book is intended to explore green solid-state techniques, eco-friendly materials involved in organic synthesis and real-time applications. Provides a broad overview of solid-state chemistry Outlines an eco-friendly solid-state synthesis of modern nanomaterials, organometallic, coordination compounds and pure organic Gives a detailed account of solid-state chemistry, fundamentals, concepts, techniques and applications Deliberates cutting-edge recent advances in industrial technologies involved in energy, environmental, medicinal and organic chemistry fields
Download or read book Vanadium Catalysis written by Manas Sutradhar and published by Royal Society of Chemistry. This book was released on 2020-11-05 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vanadium is one of the more abundant elements in the Earth’s crust and exhibits a wide range of oxidation states in its compounds making it potentially a more sustainable and more economical choice as a catalyst than the noble metals. A wide variety of reactions have been found to be catalysed by homogeneous, supported and heterogeneous vanadium complexes and the number of applications is growing fast. Bringing together the research on the catalytic uses of this element into one essential resource, including theoretical perspectives on proposed mechanisms for vanadium catalysis and an overview of its relevance in biological processes, this book is a useful reference for industrial and academic chemists alike.
Download or read book Asymmetric Metal Catalysis in Enantioselective Domino Reactions written by Helene Pellissier and published by John Wiley & Sons. This book was released on 2019-08-02 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduces an innovative and outstanding tool for the easy synthesis of complex chiral structures in a single step Covering all of the literature since the beginning of 2006, this must-have book for chemists collects the major progress in the field of enantioselective one-, two-, and multicomponent domino reactions promoted by chiral metal catalysts. It clearly illustrates how enantioselective metal-catalyzed processes constitute outstanding tools for the development of a wide variety of fascinating one-pot asymmetric domino reactions, thereby allowing many complex products to be easily generated from simple materials in one step. The book also strictly follows the definition of domino reactions by Tietze as single-, two-, as well as multicomponent transformations. Asymmetric Metal Catalysis in Enantioselective Domino Reactions is divided into twelve chapters, dealing with enantioselective copper-, palladium-, rhodium-, scandium-, silver-, nickel-, gold-, magnesium-, cobalt-, zinc-, yttrium and ytterbium-, and other metal-catalyzed domino reactions. Most of the chapters are divided into two parts dealing successively with one- and two-component domino reactions, and three-component processes. Each part is subdivided according to the nature of domino reactions. Each chapter of the book includes selected applications of synthetic methodologies to prepare natural and biologically active products. -Presents the novel combination of asymmetric metal catalysis with the concept of fascinating domino reactions, which allows high molecular complexity with a remarkable level of enantioselectivity -Showcases an incredible tool synthesizing complex and diverse chiral structures in a single reaction step -Includes applications in total synthesis of natural products and biologically active compounds -Written by a renowned international specialist in the field -Stimulates the design of novel asymmetric domino reactions and their use in the synthesis of natural products, pharmaceuticals, agrochemicals, and materials Asymmetric Metal Catalysis in Enantioselective Domino Reactions will be of high interest to synthetic, organic, medicinal, and catalytic chemists in academia and R&D departments.
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 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Synthesis of Novel Chiral Bisoxazoline Ligands for the Catalytic Asymmetric Allylic Oxidation written by Davoud Asgari and published by . This book was released on 2001 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Separation of Enantiomers written by Matthew H. Todd and published by John Wiley & Sons. This book was released on 2014-05-06 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: In one handy volume this handbook summarizes the most common synthetic methods for the separation of racemic mixtures, allowing an easy comparison of the different strategies described in the literature. Alongside classical methods, the authors also consider kinetic resolutions, dynamic kinetic resolutions, divergent reactions of a racemic mixture, and a number of "neglected" cases not covered elsewhere, such as the use of circularly polarized light, polymerizations, "ripening" processes, dynamic combinatorial chemistry, and several thermodynamic processes. The result is a thorough introduction to the field plus a long-needed, up-to-date overview of the chemical, biological, and physical methods and their applications. Newcomers to the field, students as well as experienced synthetic chemists will benefit from the highly didactic presentation: Every method is presented in detail, from relatively simple separation problems to advanced complex resolution methods.
Download or read book Bulletin of the Chemical Society of Japan written by Nihon Kagakkai and published by . This book was released on 2000 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Ethers written by C. J. Forsyth and published by . This book was released on 2008 with total page 1036 pages. Available in PDF, EPUB and Kindle. Book excerpt:
