Download or read book Application of Pd catalyzed Reactions in the Total Synthsis of Oroidin derived Alkaloids written by Manojkumar R. Bhandari and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The oroidin family of marine natural products is a growing group of sponge-derived alkaloids which contain 2-aminoimidazole and pyrrolecarboxamide fragments as their signature features. Due to their structural diversity and biological activity, many groups are interested in the total synthesis of these natural products. It has been proposed that many of the alkaloids in this family are produced in nature simply by dimerization and/or cyclization of the simplest member, oroidin. In this dissertation we have attempted to explore these biosynthetic relationships to complete the total synthesis of several oridin-derived natural products. This dissertation consists of two parts. The first part describes the total synthesis of the nominal structure of nagelamide D and the development of approaches towards total synthesis of other congeners with the nagelamide family. The second part of this dissertation describes studies of intramolecular cyclization reactions of imidazolylpropargyl amides as linchpin synthons for the assembly of imidazole-containing natural products. In the first part, a Pd-catalyzed Stille reaction was used as a transformation to construct divinyl imidazole derivatives in convergent fashion. A divergent approach was used to further functionalize intermediates obtained from Stille reaction towards the total synthesis of several nagelamides. The total synthesis of nagelamide D was accomplished by using a double Mitsunobu reaction to install pyrrolecarboxamides. Selective hydrogenation of a trisubstituted olefin or electrocyclization reactions of divinyl intermediates obtained from the Stille reaction provided key frameworks required for the total synthesis of nagelamide A, nagelamide E and ageliferin respectively. Construction of the stereoisomeric Z-vinyl stannane provided access to the divinyl imidazole fragment required for the total synthesis of nagelamide C. In the second part, Pd-catalyzed and/or base promoted intramolecular cyclization reactions of imidazolylpropargyl amides were screened as a part of diversity oriented strategy for the assembly of natural product-like frameworks. Several novel heterocycles including morpholine, pyrazinone, oxazole, pyridinone and azepin derivatives were prepared using intramolecular cyclization. Many of these heterocyclic compounds have potential to serve as intermediates en route to the total synthesis of oroidin-derived alkaloids including stevensine, nagelamide R, nagelamide T, oxocyclostylidol, agelastatin A. The potential of this approach was demonstrated in a formal total synthesis of cyclooroidin.
Download or read book Approaches Toward the Total Synthesis of Oroidin Alkaloids written by Apsara K. Herath and published by . This book was released on 2020 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nagelamides and ageliferin are oroidin-derived alkaloids which have gained the attention of the scientific community, because of their significant biological activity as well as the unprecedented structural diversity. Our work is directed toward the development of synthetic methods for the construction of oroidin dimers. Accordingly, this dissertation is composed of two sections; the chapter one provides an overview of the oroidin alkaloids with a particular focus on the nagelamide family and the third chapter describes synthetic studies towards ageliferin. The first part of chapter two focuses on the Palladium-catalyzed Stille cross-coupling reaction for the construction of the main dimeric scaffolds of the nagelamide molecules. First, we describe new methodology to synthesize the iodoimidazole fragment for use in the Stille cross-coupling reaction and subsequent progress in optimizing the yield of Stille reaction. Additional advancement of the synthesis has been achieved via azide installation in allylic and alkyl side chains of the basic framework of nagelamides A and C. A convenient method of dimethylaminosulfonyl group deprotection was reported on these advanced intermediates prior to the installation of pyrrole carboxamide moieties. The second part of chapter two details a novel approach for acylation was developed in azidecontaining imidazole systems using thio acid chemistry providing amides in one step. The reaction conditions were optimized in diverse monomeric imidazole containing-azide systems, and excellent yields of acetamide and benzamide formation were obtained. Interestingly, a newly synthesized pyrrole thio acid offers promising results for the installation of the pyrrole carboxamide moiety in oroidin-derived systems. This chemistry can be employed in the final transformation of nagelamide A and C to install the pyrrole carboxamide moieties, however; the final reaction conditions still require optimization. The third chapter describes a potential intermediate en route to ageliferin which was constructed through an intramolecular Diels-Alder reaction using 4-vinylimidazole tethered to a urazole as the starting material. The Diels-Alder precursor was synthesized through palladium-catalyzed TsujiTrost cross-coupling reaction between t-butyl carbonate protected vinylimidazole and Nphenylurazole in excellent yield. We have explored three different protecting groups (DMAS, Bn, and SEM) on the imidazole nitrogen which can affect both the Diels-Alder reactivity and the electronic nature of the tetrahydrobenzimidazole ring system. For example, this can influence the oxidative rearrangement and introduction of the C2-amino moiety at the later in the synthesis. Further studies are in progress to complete the total synthesis of ageliferin using these advanced intermediates.
Download or read book Recent Applications of Selected Name Reactions in the Total Synthesis of Alkaloids written by Majid M. Heravi and published by Elsevier. This book was released on 2021-06-12 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent Applications of Selected Name Reactions in the Total Synthesis of Alkaloids includes comprehensive coverage of name reactions in the synthesis of alkaloids. This book highlights the synthesis of various alkaloids using special name reactions including the Diels-Alder, Friedel-Crafts, Heck, Mannich, Pauson-Khand, Pictet-Spengler, Sonogashira and Suzuki reactions. In this book, some selected name reactions in the total synthesis of alkaloids are covered, as they can be used as the key step/steps in the synthesis of different alkaloids exhibiting various biological activities. All chapters include an introduction, history and mechanism of the name reaction, and present the origin of the natural product and its known biological activities. The pathway to total synthesis is visually illustrated, and the focus is on the step in which a name reaction is applied. Chemists working in the area of synthetic organic chemistry will find this reference useful, as well as those working to develop novel methodologies for the synthesis of natural products in both academia and industry. This book is also beneficial to biologists, pharmacists and botanists. - Includes an introduction of alkaloids, their origins and biological properties - Features the applications of special name reactions as the key step in the total synthesis of featured alkaloids - Covers the pathway for the synthesis of alkaloids from commercially available or easily accessible starting materials by using at least one name reaction to achieve the desired target products
Download or read book Applications of Dihydroarenediols to Chemoenzymatic Synthesis written by Kevin J. Finn and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present studies describe, as a primary goal, our recent progess toward the synthesis of morphine alkaloids from aromatic precursors. Model substrates were synthesized which allowed investigation into Diels-Alder, radical cascade, and palladium-catalyzed bond-forming reactions as possible routes to the morphine alkaloid skeleton. As a secondary objective, three separate series of aromatic substrates were subjected to whole-cell oxidation with Escherichia coli JM 109 (pDTG601), a recombinant organism over-expressing the enzyme toluene dioxygenase. Included in this study were bromothioanisoles, dibromobenzenes, and cyclopropylbenzene derivatives. The products of oxidation were characterized by chemical conversion to known intermediates. The synthetic utility of one of these bacterial metabolites, derived from oxidation of o-dibromobenezene, was demonstrated by chemical conversion to (-)conduritol E.
Download or read book Development of Zinc and Palladium catalyzed Asymmetric Transformations for Total Synthesis of Alkaloids and Other Bioactive Compounds written by Chao-I Hung and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Leveraging Propargylic Frameworks in the Total Synthesis of Natural Products Containing a 2 aminoimidazole written by Ravi P. Singh (Ph.D.) and published by . This book was released on 2020 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our group is mainly interested in the total synthesis of marine sponge-derived 2-aminoimidazole-containing alkaloids. A new family of 2-aminoimidazole alkaloids, the Leucetta alkaloids, is a group of >60, 2-aminoimidazole natural products found in marine sponges. Our lab is also interested in the total synthesis of oroidin-based pyrrole-imidazole containing marine sponge-derived alkaloids. These natural products are a growing class of alkaloids with exotic connectivity, unique topologies, and high nitrogen content. The presence of 2-aminoimidazole and pyrrolecarboxamide fragments in their framework represent the signature structural features. Recently, these secondary metabolites have received substantial attention because of their challenging structures and strong biological activities.This dissertation consists of two parts. The first part specifically addresses a problem pertaining to the total synthesis of two family members of Leucetta alkaloids; spirocalcaridines A and B through the development of a novel method for the de novo construction of imidazole ring. Specifically, hypervalent iodine (III) mediated oxidative dearomatizing spirocyclization of propargyl guanidines was developed to construct the complete skeletal core present in spirocalcaridine A and B. A survey of the reactivity of these advanced intermediates was undertaken in an effort to complete the total synthesis. While significant advancements were uncovered, the completionof the total synthesis remain to be accomplished. Also, while exploring this transformation, a number of novel reactions were developed. Chapter 2 discusses the development of an unusual one-pot N-cyanation-spirocyclization reaction of propargylamines leading directly to the spiro-fused cyclohexadienone. Chapter 3 focuses on the development of tandem thioacylation-intramolecular hydrosulfenylation of propargylamines to access 2-aminothiazolidines.The second part discusses the utilization of a more traditional approach by functionalizing an existing imidazole ring for the completion of the total synthesis of two oroidin family members; hymenin and 2-debromohymenin. A convenient 9-step synthesis of these pyrroloazepinone containing natural products from a commercially available iodoimidazole via a key gold-catalyzed hydroarylation was achieved.Elaboration of the pyrroloazepinone through reduction, C2-azidation delivered the key late stage intermediates. Chemoselective reduction of the C2-azide and reductivecleavage of N-methoxy group with molybdenum hexacarbonyl delivered the two hymenin congeners in good yield.
Download or read book Classics in Total Synthesis III written by K. C. Nicolaou and published by John Wiley & Sons. This book was released on 2011-03-14 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: K.C. Nicolaou - Winner of the Nemitsas Prize 2014 in Chemistry Adopting his didactically skillful approach, K.C. Nicolaou compiles in this textbook the important synthetic methods that lead to a complex molecule with valuable properties. He explains all the key steps of the synthetic pathway, highlighting the major developments in blue-boxed sections and contrasting these to other synthetic methods. A wonderful tool for learning and teaching and a must-have for all future and present organic and biochemists.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2009 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2002 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Marine Antifouling Coatings and Technologies written by Claire Hellio and published by Elsevier. This book was released on 2009-05-22 with total page 785 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine biofouling can be defined as the undesirable accumulation of microorganisms, algae and animals on structures submerged in seawater. From the dawn of navigation, marine biofouling has been a major problem for shipping in such areas as reduced speed, higher fuel consumption and increased corrosion. It also affects industries using off-shore structures such as oil and gas production and aquaculture. Growing concerns about the environmental impact of antifouling coatings has led to major new research to develop more environmentally-friendly alternatives. Advances in marine antifouling coatings and technologies summaries this wealth of research and its practical implications.This book is divided into four sub-sections which discuss: marine fouling organisms and their impact, testing and development of antifouling coatings, developments in chemically-active marine antifouling technologies, and new surface approaches to the control of marine biofouling. It provides an authoritative overview of the recent advances in understanding the biology of fouling organisms, the latest developments on antifouling screening techniques both in the field and in the laboratory, research on safer active compounds and the progress on nontoxic coatings with tailor-made surface properties.With its distinguished editors and international team of contributors, Advances in marine antifouling coatings and technologies is a standard reference for manufacturers of marine antifouling solutions, the shipping industry, oil and gas producers, aquaculture and other industries using offshore structures, and academics researching this important area. - Assesses marine antifouling organisms and their impact, including a historical review and directions for future research - Discusses developments in antifouling coatings examining chemically-active and new surface approaches - Reviews the environmentally friendly alternative of safer active compounds and the progress of non-toxic compounds
Download or read book Superbases for Organic Synthesis written by Tsutomu Ishikawa and published by John Wiley & Sons. This book was released on 2009-01-26 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Guanidines, amidines and phosphazenes have been attracting attention in organic synthesis due to their potential functionality resulting from their extremely strong basicity. They are also promising catalysts because of their potential for easy molecular modification, possible recyclability, and reduced or zero toxicity. Importantly, these molecules can be derived as natural products – valuable as scientists move towards “sustainable chemistry”, where reagents and catalysts are derived from biomaterial sources. Superbases for Organic Synthesis is an essential guide to these important molecules for preparative organic synthesis. Topics covered include the following aspects: an introduction to organosuperbases physicochemical properties of organic superbases amidines and guanidines in organic synthesis phosphazene: preparation, reaction and catalytic role polymer-supported organosuperbases application of organosuperbases to total synthesis related organocatalysts: proton sponges and urea derivatives amidines and guanidines in natural products and medicines Superbases for Organic Synthesis is a comprehensive, authoritative and up-to-date guide to these important reagents for organic chemists, drug discovery researchers and those interested in the chemistry of natural products.
Download or read book Modern Alkaloids written by Ernesto Fattorusso and published by John Wiley & Sons. This book was released on 2008-01-08 with total page 689 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents all important aspects of modern alkaloid chemistry, making it the only work of its kind to offer up-to-date and comprehensive coverage. While the first part concentrates on the structure and biology of bioactive alkaloids, the second one analyzes new trends in alkaloid isolation and structure elucidation, as well as in alkaloid synthesis and biosynthesis. A must for biochemists, organic, natural products, and medicinal chemists, as well as pharmacologists, pharmaceutists, and those working in the pharmaceutical industry.
Download or read book Reactivity of P H Group of Phosphorus Based Compounds written by Kolio D. Troev and published by Academic Press. This book was released on 2017-09-06 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactivity of P-H Group of Phosphorus Based Compounds bridges the gap between inorganic and organic phosphorus compounds, providing a basis to explore the myriad possibilities for synthesis of novel low and high molecular phosphorus-containing compounds. It covers well-documented reactions in detail, including: tautomerization, oxidation, reduction, alkylation, oxidation coupling, addition reaction to: carbon-carbon multiple bonds, Schiff base, isocyanates, nitriles, epoxides; addition to carbonyl group, Kabachnik- Fields reaction, cross-coupling reaction and more. In an accessible style complete with synthetic routes and figures, the resource then covers the reactivity of multiple P-H group members: phosphines, phosphine oxides, hypophosphorus acid, H-phosphinic acids and polys(alkylene H-phosphonate). This valuable coverage supports the advancement of research and applications in this area for scientists solving a scientific problem or starting a variety of new projects, such as a new reaction for the synthesis of biologically active compounds, new methods of polymer synthesis or a new methodology for polymer modification. - Describes the diverse reactivity of the phosphorus-hydrogen group, perhaps the most powerful in organic chemistry - Includes practical information for the synthesis of catalysts, biologically active substances, flame retardants, advance materials and polymer materials - Offers a visually-accessible guide to important reactions by an internationally recognized chemist
Download or read book Bioactive Marine Natural Products written by Dewan S. Bhakuni and published by Springer Science & Business Media. This book was released on 2006-06-30 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bioactive Marine Natural Products is the first book available that covers all aspects of bioactive marine natural products. It fills the void in the literature for bioactive marine natural products. The book covers various aspects of marine natural products and it is hoped that all the major classes of bioactive compounds are included. Different classes of marine organisms and the separation and isolation techniques are discussed. The chemistry and biology of marine toxins, peptides, alkaloids, nucleosides and prostanoids are discussed in detail. Biological, toxicological and clinical evaluations are also dealt with to ensure that the book may be adopted at any stage by any practicing organic chemist or biologist, working in academia or in R and D divisions of pharmaceutical companies. Each chapter in the book includes an abstract to highlight the major points discussed in the text and concluding remarks are given. References to books, monographs, review articles and original papers are provided at the end of each chapter.
Download or read book Bioorganic Chemistry written by Ulf Diederichsen and published by John Wiley & Sons. This book was released on 1999-12-16 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: The understanding of (patho)physiological processes - the biosynthesis of biomolecules such as enzymes, nucleic acids, and secondary metabolites; the pathways of signaltransduction; or the function of pharmaceutical agents - is of increasing importance not only for drug research but also for the development of new synthetic methods in organic chemistry and biochemistry. In a truly interdisciplinary way bioorganic chemistry unites the central questions of biochemistry, medicinal chemistry, organic chemistry, and spectroscopy. This book fills a void in this rapidly growing field of chemistry and gives a thorough yet understandable introduction for advanced students and researchers alike. Contributions of more than sixty scientists provide a topical overview of recent advances in: drug development based on natural products; the biosynthesis, activity, and application of enzymes; carbohydrates; peptides; nucleic acids; analytical methods in bioorganic chemistry. This book will be an appetizer for all - students and researchers alike - seeking orientation in this fascinating field of chemistry.
Download or read book Herbivores Their Interactions with Secondary Plant Metabolites written by and published by Academic Press. This book was released on 2012-12-02 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents the latest research on herbivores, aquatic and terrestrial mammals and insects. The Second Edition, written almost entirely by new authors, effectively complements the initial work. It includes advances in molecular biology and microbiology, ecology, and evolutionary theory that have been achieved since the first edition was published in 1979. The book also incorporates relatively new methodologies in the area of molecular biology, like protein purification and gene cloning. Volume II, Ecological and Evolutionary Processes, also opens up entirely new subjects: The discussions of interactions have expanded to include phenomena at higher trophic levels, such as predation and microbial processing and other environmental influences. Both this and Volume I, The Chemical Participants, will be of interest to chemists, biochemists, plant and insect ecologists, evolutionary biologists, physiologists, entomologists, and agroecologists interested in both crop and animal science. - Presents coevolution of herbivores and host plants - Examines resource availability and its effects on secondary metabolism and herbivores - Studies physiology and biochemistry of adaptation to hosts - Includes tri-trophic interactions involving predators and microbes
Download or read book Physical Chemistry A Molecular Approach written by Donald A. McQuarrie and published by Sterling Publishing Company. This book was released on 1997-08-20 with total page 1396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Emphasizes a molecular approach to physical chemistry, discussing principles of quantum mechanics first and then using those ideas in development of thermodynamics and kinetics. Chapters on quantum subjects are interspersed with ten math chapters reviewing mathematical topics used in subsequent chapters. Includes material on current physical chemical research, with chapters on computational quantum chemistry, group theory, NMR spectroscopy, and lasers. Units and symbols used in the text follow IUPAC recommendations. Includes exercises. Annotation copyrighted by Book News, Inc., Portland, OR
