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 Selective Epoxidations of Olefins Allylic Alcohols and Homoallylic Alcohols with Tert butyl Hydroperoxide and Molybdenum Vanadium and Titanium Catalysts written by Bryant Edwin Rossiter and published by . This book was released on 1982 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Chemical Calculation on Catalytic Epoxidation by Vanadium Complexes written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The epoxidation of three stereolabeled methyl-substituted chiral allylic alcohols with an allylic strain, namely 3-methylbut-3-en-2-ol (r1), trans-pent-3-en-2-ol (r2) and cis-pent-3-en-2-ol (r3), has been studied by the density functional theory method, B3LYP/6-31G(d). For the VO(OH)[subscript 3]/H[subscript 2]O[subscript 2] oxidant, the vanadium (V) metal rapidly exchanges its ligands for the hydrogen peroxide and allylic alcohol (step 1 and 2). The latter is coordinative activated for oxygen transfer through its enhanced electrophilic character (step 3). And final step is the ligand-substitution to give products and release catalysts. For each substrate, the free energies of intermediate complexes, their threo and erytho transition state, and the corresponding product complexes were calculated. The threo:erytho product ratios have been estimated from the computed free-energies for the competing threo and erytho transition states to be 99.7:0.3 (r1),80.9:19.1 (r2) and 72.2:27.8 (r3).
Download or read book Part I Vanadium catalyzed Asymmetric Oxidative Coupling of Phenols and Hydroxycarbazoles and Its Mechanistic Study written by Houng Kang and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part I: The axially chiral biaryl motif is found in many natural products as well as in ligands for catalysis such as 1,1'-binaphthol. Formation of axially chiral compounds was accomplished by means of the asymmetric oxidative coupling, which has proven to be both an efficient and environmentally benign synthetic method. Interests toward an effective asymmetric oxidative coupling of simple phenols, which are challenging substrates because of relatively high oxidation potential and regioselectivity issues, have arisen due to a lack of corresponding methods. After many efforts to design and modify the catalyst scaffold, we found that a monomeric vanadium(V) catalyst together with LiCl or HOAc as an additive accomplished C-C bond formation to afford the bisphenol moiety in good yield and good enantioselectivity. The carbazole moiety is another good candidate to apply our oxidative coupling method because of its electron-rich nature. Using various 3-substituted-2-hydroxycarbazole derivatives, oxidative coupling afforded products containing diverse functional groups, including ketone, ester, trifluoromethyl, halides, allyl, etc. Part II: The azaphilone alkaloid, chaetoglobin A, has drawn attention due to its intriguing dimeric structure. The molecule features a 2H-isoquinoline-6,8-dione moiety containing quaternary centers and a chiral axis that connects two identical motifs. Although a variety of monomeric azaphilone alkaloids have been synthesized, a dimeric class of azaphilone has not been synthesized to date. Installing axial chirality by means of the asymmetric oxidative phenol coupling is the key step in making the natural product. Afterwards, bisformylation and oxidative dearomatization were carried out smoothly to afford highly oxygenated bicyclic cores. Thorough optimization of the selective acetyl deprotection and final amination afforded access to the synthetic chaetoglobin A in 12 linear steps. Part III: These days, the ligand plays an important role in versatile chemical reactions. Understanding the ligand effect provided critical information to tackle challenging issues. Taking advantage of High Throughput Experimentation (HTE) allowed access to a variety of ligands in a rapid and efficient manner. Due to easy synthesis of a series of different alkynylphosphine oxides and azides, our efforts were focused on generating the diverse triazole-based phosphine ligands. The ligand was prepared by [3+2]-cycloaddition with the alkynylphosphine oxide and azide, followed by the corresponding phosphine oxide reduction. Ultimately, a one-pot protocol reinforced the efficient ligand synthesis and accomplished the synthesis of a number of ligands by HTE parallel synthesis. Currently, with the ClickPhos ligands, the ligand effect was explored under the challenging chemical reaction conditions. Part IV: 2,2-Disubstituted indolin-3-one is not only a core structure for many natural products but also serves as a useful synthetic intermediate. To construct the C-2 quaternary center via the oxidative coupling between 3-oxindole and various aryl substrates, including indoles, pyrroles, and electron-rich aryl compounds, was achieved in the presence of a copper catalyst incorporated with a salan ligand. This milder catalytic protocol efficiently generated the quaternary center with various functional groups tolerance, such as halide, ester, nitrile, etc. In addition, use of a chiral monomeric vanadium catalyst gave promising levels of asymmetric transformation.
Download or read book Natural Product Biosynthesis written by Christopher T. Walsh and published by Royal Society of Chemistry. This book was released on 2017-04-28 with total page 787 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook describes the types of natural products, the biosynthetic pathways that enable the production of these molecules, and an update on the discovery of novel products in the post-genomic era.
Download or read book Catalytic Asymmetric Synthesis written by Takahiko Akiyama and published by John Wiley & Sons. This book was released on 2022-05-27 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytic Asymmetric Synthesis Seminal text presenting detailed accounts of the most important catalytic asymmetric reactions known today This book covers the preparation of enantiomerically pure or enriched chemical compounds by use of chiral catalyst molecules. While reviewing the most important catalytic methods for asymmetric organic synthesis, this book highlights the most important and recent developments in catalytic asymmetric synthesis. Edited by two well-qualified experts, sample topics covered in the work include: Metal catalysis, organocatalysis, photoredox catalysis, enzyme catalysis C–H bond functionalization reactions Carbon–carbon bond formation reactions, carbon–halogen bond formation reactions, hydrogenations, polymerizations, flow reactions Axially chiral compounds Retaining the best of its predecessors but now thoroughly up to date with the important and recent developments in catalytic asymmetric synthesis, the 4th edition of Catalytic Asymmetric Synthesis serves as an excellent desktop reference and text for researchers and students, from upper-level undergraduates all the way to experienced professionals in industry or academia.
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 Analytical Determination of Nicotine and Related Compounds and their Metabolites written by J.W. Gorrod and published by Elsevier. This book was released on 1999-11-02 with total page 773 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides for the first time a single comprehensive source of information on the analytical chemistry of nicotine and related alkaloids. The editors have brought together scientists from academia and the tobacco industry to describe the state-of-the-art of the chemistry and analytical methods for measurement of nicotine. Both the scope and detail of the book are impressive. Chapters describe the history, pharmacology and toxicology of nicotine, the biosynthesis of nicotine and other alkaloids in the tobacco plant, the general chemistry of nicotine and the analytical methodologies that have been used to measure nicotine and related alkaloids in biological specimens, in tobacco and pharmaceutical products and in tobacco smoke. There is also a comprehensive review of the chemistry and toxicology of nicotine-derived nitrosamines, an important class of tobacco carcinogens.
Download or read book Stereoselective Synthesis written by Mihály Nógrádi and published by John Wiley & Sons. This book was released on 2008-07-11 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: The state-of-the-art in stereoselective synthesis! Thoroughly revised and updated, this enlarged second edition offers a plethora of valuable information on methods and reagents in stereoselective synthesis. Methods have been selected for high efficiency and selectivity; mechanistic aspects are treated succinctly, with a strong emphasis on practical applications. For this new edition, material has been added on * homogeneous diastereoselective hydrogenations * enantioselective oxidations * novel, efficient chiral auxiliaries Much of the information given is presented in figures and tables, which makes the book a valuable reference work for the practically minded organic chemist. From reviews of the first edition: 'The extensive material in the volume should prove particularly useful to anyone involved in synthetic chemistry or teaching a course in organic chemistry.' Journal of Medicinal Chemistry 'With nearly 1400 references cited, the book contains a wealth of information and should be a useful addition to the chemist's library.' The American Scientist
Download or read book Modern Organic Synthesis written by George S. Zweifel and published by John Wiley & Sons. This book was released on 2017-03-13 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book bridges the gap between sophomore and advanced / graduate level organic chemistry courses, providing students with a necessary background to begin research in either an industry or academic environment. • Covers key concepts that include retrosynthesis, conformational analysis, and functional group transformations as well as presents the latest developments in organometallic chemistry and C–C bond formation • Uses a concise and easy-to-read style, with many illustrated examples • Updates material, examples, and references from the first edition • Adds coverage of organocatalysts and organometallic reagents
Download or read book Strategic Applications of Named Reactions in Organic Synthesis written by Laszlo Kurti and published by Elsevier. This book was released on 2005-04-29 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt: Kurti and Czako have produced an indispensable tool for specialists and non-specialists in organic chemistry. This innovative reference work includes 250 organic reactions and their strategic use in the synthesis of complex natural and unnatural products. Reactions are thoroughly discussed in a convenient, two-page layout--using full color. Its comprehensive coverage, superb organization, quality of presentation, and wealth of references, make this a necessity for every organic chemist. * The first reference work on named reactions to present colored schemes for easier understanding* 250 frequently used named reactions are presented in a convenient two-page layout with numerous examples* An opening list of abbreviations includes both structures and chemical names * Contains more than 10,000 references grouped by seminal papers, reviews, modifications, and theoretical works * Appendices list reactions in order of discovery, group by contemporary usage, and provide additional study tools* Extensive index quickly locates information using words found in text and drawings
Download or read book Metal Organic Frameworks as Heterogeneous Catalysts written by Francesc X. Llabrés i Xamena and published by Royal Society of Chemistry. This book was released on 2013-07-01 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the latest research and discovery in the use of MOFs in catalysis, highlighting the extent to which these materials have been embraced by the community.
Download or read book Glycoscience written by Bertram O. Fraser-Reid and published by Springer Science & Business Media. This book was released on 2008-04-14 with total page 2847 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a reflection of the quantum leap that has been made in the study of glycostructures, the first edition of this book has been completely revised and updated. The editors give up-to-date information on glycostructures, their chemistry and chemical biology in the form of a completely comprehensive survey. Glycostructures play highly diverse and crucial roles in a myriad of organisms and important systems in biology, physiology, medicine, bioengineering and technology. Only in recent years have the tools been developed to partly understand the highly complex functions and the chemistry behind them. While many facts remain undiscovered, this MRW has been contributed to by a large number of the world’s leading researchers in the field.
Download or read book Synthesis of Marine Natural Products 2 written by K.F. Albizati and published by Springer. This book was released on 2011-12-16 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volumes five and six of Bioorganic Marine Chemistry differ from their predecessors in two respects - they deal exclusively with laboratory synthesis of marine natural products and they represent the effort of a single author and his associates. The rationale for these departures is readily perceived. For several decades organic synthesis has without doubt been the most spectacular branch of organic chemistry. While the late R.B. Woodward's dictum - organic compounds can undergo only four basic reactions: they can gain electrons; they can lose electrons; they can be transformed with acid or with base - is still true, the wealth and variety of available reagents which will accomplish chemical transformations has reached staggering proportions. Little wonder then, that synthetic methodology has achieved a high degree of predictability and total synthesis of natural products has been successfully directed toward ever more challenging targets. As for the second point, that of single authorship, multiple authorship would invariably have led to gaps and overlaps, thus making it difficult to assemble and assess recent research in a systematic and comprehens ive fashion.
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 The Activation of Dioxygen and Homogeneous Catalytic Oxidation written by D.H.R. Barton and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 503 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph consists of the proceedings of the Fifth International Symposium on the Activation of Dioxygen and Homogeneous Catalytic Oxidation, held in College Station, Texas, March 14-19, 1993. It contains an introductory chapter authored by Professors D. H. R. Barton and D. T. Sawyer, and twenty-nine chapters describing presentations by the plenary lecturers and invited speakers. One of the invited speakers, who could not submit a manuscript for reasons beyond his control, is represented by an abstract of his lecture. Also included are abstracts of forty-seven posters contributed by participants in the symposium. Readers who may wish to know more about the subjects presented in abstract form are invited to communicate directly with the authors of the abstracts. This is the fifth international symposium that has been held on this subject. The first was hosted by the CNRS, May 21-29, 1979, in Bendor, France (on the Island of Bandol). The second meeting was organized as a NATO workshop in Padova, Italy, June 24-27, 1984. This was followed by a meeting in Tsukuba, Japan, July 12-16, 1987. The fourth symposium was held at Balatonfured, Hungary, September 10-14, 1990. The sixth meeting is scheduled to take place in Delft, The Netherlands (late Spring, 1996); the organizer and host will be Professor R. A. Sheldon.
Download or read book Applied Cross Coupling Reactions written by Yasushi Nishihara and published by Springer Science & Business Media. This book was released on 2012-12-14 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: “Applied Cross-Coupling Reactions” provides students and teachers of advanced organic chemistry with an overview of the history, mechanisms and applications of cross-coupling reactions. Since the discovery of the transition-metal-catalyzed cross-coupling reactions in 1972, numerous synthetic uses and industrial applications have been developed. The mechanistic studies of the cross-coupling reactions have disclosed that three fundamental reactions: oxidative addition, transmetalation, and reductive elimination, are involved in a catalytic cycle. Cross-coupling reactions have allowed us to produce a variety of compounds for industrial purposes, such as natural products, pharmaceuticals, liquid crystals and conjugate polymers for use in electronic devices. Indeed, the Nobel Prize for Chemistry in 2010 was awarded for work on cross-coupling reactions. In this book, the recent trends in cross-coupling reactions are also introduced from the point of view of synthesis design and catalytic activities of transition-metal catalysts.
