Download or read book Methodologies of Bicyclo 2 2 2 octane Compounds and Progress Toward the Total Synthesis of Parthenolide written by Courtney Arielle Roberts and published by . This book was released on 2016 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Chapter 1, rearrangements of 4-substituted bicyclo[2.2.2]oct-2-enyl-5-selenophenyl esters are explored. Reduction of the esters under radical-generating conditions initially generates a bicyclo[2.2.2]oct-5-en-2-yl radical which can rearrange to a bicyclo[3.2.1]oct-6-en-2-yl radical via a cyclopropylcarbinyl radical. Although the bicyclo[3.2.1]octene system exhibits greater strain than does the bicyclo[2.2.2]octene system, radical-stabilizing substituents can reverse this preference. The product ratios are influenced by the interplay of ring strain and radical stability. In addition, the rearranged products favored the equatorial over the axial isomers, which can be explained by torsional steering. In Chapter 2, different approaches to the synthesis of the optically active bicyclo[2.2.2]octane-2,5-diones are presented. A stereoselective Diels-Alder cycloaddition was explored to construct the bicyclo[2.2.2]octane skeleton in an efficient manner. This approach was hindered by unexpected polymerization and lack of stereoselectivity. A different method of synthesizing the optically active bicyclo[2.2.2]octane-2,5-dione featuring a diastereoselective 1,4-addition is also presented. In Chapter 3, progress toward the total synthesis of parthenolide is described. The synthetic route relies on ring-closing metathesis to close the 10-membered carbocycle of the natural product. The efforts leading up to and including the key ring-closing step are described. Specific attention is given to different methods for overcoming the difficulties associated with medium-sized ring formation.
Download or read book Work Towards the Total Synthesis of Patchouli Alcohol and Approaches to Cycloseychellene written by Murray Douglas Bailey and published by . This book was released on 1986 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cycloaddition Chemistry for the Synthesis of Heterocyclic Compounds and Progress Towards the Total Synthesis of Grandilodine A written by Andrew Charles Stevens and published by . This book was released on 2013 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes three separate research projects within the broad topic of synthetic organic chemistry. The synthesis of alkyl-substituted siloles and their reactivity in Diels-Alder chemistry is reported. Furthermore, the cleavage of the bicyclic adducts by Tamao-Fleming oxidation has been achieved which reveals a highly substituted cyclohexene-1,4-diol structure. The second chapter describes the cycloaddition chemistry of alkoxy-activated cyclobutane dicarboxylates with aldehydes, nitrones and nitrosoarenes. The cycloaddition occurs, in the case of aldehydes, with uniformly high diastereoselectivity to afford tetrahydropyrans in good to excellent yield. When nitrones were used as the dipolarophile the cycloaddition occurs in a rather unselective manner though the formed oxazepanes undergo equilibration to yield single diastereomers in most cases. The cycloaddition with nitrosoarenes, however, proved an exception as the regioselectivity of the reaction was dependant both on the nitrosoarenes and the catalyst employed. Lastly, progress towards the synthesis of grandilodine A is reported. Several routes were developed in attempts to form the central 8-membered ring; however, successful ring closure has eluded this study.
Download or read book Progress Toward the Synthesis of dibromophakellin and Congeners written by Francisco Miguel Franco-Torres and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The pyrrole-imidazole alkaloid family of natural products illustrates the diversity of topographically unique molecules with potent biological activities that can be found in the marine environment. Thus, great interest for this class of compounds has developed leading to new synthetic methodologies and tactics to build these complex secondary metabolites. The overall objectives of this research project include the total synthesis of the phakellins and phakellstatins. First, we revisited the strategy developed in our group for the total synthesis of (+)-dibromophakellstatin and utilized it for the synthesis of its naturally occurring enantiomer and congeners. Second, we proposed and studied a new and more concise approach to the phakellstatins and phakellins based on a key C-H insertion process developed by Du Bois. Attempts to streamline the first synthesis of (+)-dibromophakellstatin proved to be quite challenging. Shortcomings in the reproducibility of some parts of the original strategy precluded us from completing and making more efficient the synthesis of the natural enantiomer ( - )-dibromophakellstatin. Fortuitously, our second generation approach though it presented itself as an efficient route to the phakellins and phakellstatins produced the undesired anti diastereomer of the key guanidine intermediate which precluded our study of the pivotal C-H insertion reaction.
Download or read book Prins Pinacol Synthesis of Bicyclo 331 nonanones and Application Towards the Total Synthesis of Papuaforin A written by Maxime Riou and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present thesis concentrates on the development of the Prins-Pinacol mediated synthesis of bicyclo[3.3.1]nonanones and its application towards the total synthesis of papuaforin A. In addition, an exploratory study of the oxy-Cope/Claisen/ene cascade reaction and the total synthesis of (+)-isofregenedol are presented. These subjects are divided into four chapters. The first part of this thesis describes the discovery and examination of a novel microwave-induced rearrangement of propargyl vinyl ethers delivering cis-bicyclic unsaturated lactones. The methodological investigation of the Prins-Pinacol rearrangement oriented towards the construction of bicyclo[3.3.1]nonanones is discussed in Chapter 3. The synthesis of various precursors and the optimization of the key step are presented. The reactivity observed for the isopropylidene and benzylidene oxocarbenium precursors is then compared. The effect of the substitution of the alkene moiety and at the ring junction is also examined. The Prins-Pinacol rearrangement of complex Diels-Alder cycloadducts is described last. The fourth chapter depicts the advancement towards the total synthesis papuaforin A. The synthesis of a model compound possessing the bicyclo[3.3.1]nonanone core of the natural product is first presented. The progress towards the actual total synthesis is discussed next. Finally, the application of the gold(I)-catalyzed benzannulation of hydroxyenynes to the de novo synthesis of (+)-isofregenedol is described in Chapter 5.
Download or read book Synthesis and Studies of Compounds Related to Bicyclo 3 3 0 Octane and Pentalene written by Hsi-kwei Chiang and published by . This book was released on 1952 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 2 2 Photocycloaddition in Natural Product Synthesis written by Roel Klein Nijenhuis and published by . This book was released on 2018 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: [2+2]-Photocycloaddition is a powerful method to synthesise highly strained, complex and multicyclic compounds. The research described in this thesis focusses on using this reaction to pursue the total synthesis of a number of complex natural products. The main project focusses on the synthesis of solanoeclepin A, an extremely potent hatching agent of the potato cyst nematode. To reach this goal, the molecule was divided in two parts, the left- and the right-hand substructure. With the left-hand substructure completed in previous research, the goal was now to synthesise the right-hand substructure, and to complete the total synthesis by connecting the two fragments. The key step is a [2+2]-photocycloaddition of 2-substituted 3-methyl-2-cyclohexenones, described in chapter 3. Using this reaction the highly strained bicyclo[2.1.1]cyclohexane core structure of the natural product was accessed from simple starting materials in a few steps. A racemic approach to the right-hand substructure of solanoeclepin A is described in chapter 2. Extensive research ultimately led to a short and efficient enantioselective formal synthesis of solanoeclepin A, as described in chapter 4. Finally, the efforts to combine both fragments are described in chapter 5. The final chapter describes the first total syntheses of aquatolide and wilfolide B. Aquatolide was prepared using the [2+2]-photocycloaddition of an allene-substituted pentenolide, ultimately leading to the natural product. Retro-ene type rearrangement of the cycloaddition product led to a different carbon skeleton, leading to the successful total synthesis of wilfolide B.
Download or read book I The Photolysis of 2 cyclopropylcyclohexanone written by Edward L. Biersmith and published by . This book was released on 1969 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Progress Toward the Total Synthesis of the Epoxyquinoid Family of Natural Products written by and published by . This book was released on 2007 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enyne metathesis is a powerful C-C bond forming reaction that combines an alkene and an alkyne and forms a conjugated 1,3-diene. The scope of enyne metathesis was expanded by combining various alkynes with vinyl ethers. Typically vinyl ethers are poor metathesis substrates, but a method was developed for the synthesis of dienol ethers utilizing ruthenium carbenes. The products of these reactions were subjected to [4+2] cycloaddition conditions to give substituted cyclohexene rings. The epoxyquinoid family is a highly targeted series of natural products. A general method for the synthesis of the core structure of these natural products has been explored. An enyne cross metathesis/ring closing metathesis step was designed as the key reaction to this synthesis. A Darzen's condensation between a chiral [alpha]-alkoxy aldehyde and a chloroacyl oxazolidinone was successfully employed to join two fragments of the molecule as well as to install an epoxide. A highly diastereoselective cuprate addition set the stereochemistry of the first stereogenic center. The early intermediates were prepared via easily scalable organic syntheses procedures including utilizing a carbohydrate as the source of chirality. Ring closing enyne metathesis to form the epoxyquinoid core was evaluated in two epimeric series.
Download or read book Chemistry for Pharmacy Students written by Professor Satyajit D. Sarker and published by John Wiley & Sons. This book was released on 2013-05-28 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book has succeeded in covering the basic chemistry essentials required by the pharmaceutical science student... the undergraduate reader, be they chemist, biologist or pharmacist will find this an interesting and valuable read." –Journal of Chemical Biology, May 2009 Chemistry for Pharmacy Students is a student-friendly introduction to the key areas of chemistry required by all pharmacy and pharmaceutical science students. The book provides a comprehensive overview of the various areas of general, organic and natural products chemistry (in relation to drug molecules). Clearly structured to enhance student understanding, the book is divided into six clear sections. The book opens with an overview of general aspects of chemistry and their importance to modern life, with particular emphasis on medicinal applications. The text then moves on to a discussion of the concepts of atomic structure and bonding and the fundamentals of stereochemistry and their significance to pharmacy- in relation to drug action and toxicity. Various aspects of aliphatic, aromatic and heterocyclic chemistry and their pharmaceutical importance are then covered with final chapters looking at organic reactions and their applications to drug discovery and development and natural products chemistry. accessible introduction to the key areas of chemistry required for all pharmacy degree courses student-friendly and written at a level suitable for non-chemistry students includes learning objectives at the beginning of each chapter focuses on the physical properties and actions of drug molecules
Download or read book Stereoselective Biocatalysis written by Ramesh N. Patel and published by CRC Press. This book was released on 2000-01-03 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers an explanation of the specific ways that biocatalysis outperforms chemical catalysis by: utilizing ambient temperature and atmospheric pressure to minimize problems of isomerization, racemization, and epimerization; employing microbial cells and enzymes that can be immobilized and reused over many cycles; and overexpressing enzymes for greater economy and efficiency.
Download or read book Spillover and Mobility of Species on Solid Surfaces written by A. Guerrero-Ruiz and published by Elsevier. This book was released on 2001-08-02 with total page 501 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Spillover and Mobility of Species and Solid Surfaces" collects the papers which were presented at the Fifth International Conference Spillover, either as oral or poster contributions, as well as the summaries of the invited lectures. This congress and its publication in the Studies on Surface Science and Catalysis series follow the tradition of previous conferences on spillover, initiated in Lyon, 1983, and continued in Leipzig, 1989, Kyoto 1993 and Dalian, 1997. For the fifth conference, held in S.L. el Escorial (Madrid), the organising committee has attempted to compile representative contributions which illustrate the advances in understanding the spillover phenomenon since 1997. Spillover is a process taking place during the interface of gas reactant molecules (mainly hydrogen and oxygen) on solid surfaces. However, different contributions to the more general area of the chemistry at surfaces, related with the mobility and migration of species, diffusion through membranes, fuel cell catalysts, etc., have also been included. In fact the title of the present volume summarizes this attempt to extend the conference topics towards dynamics at surfaces.Among the 70 contributions received, the 56 accepted papers were selected on the basis of the reports of at least two international reviewers, according to standards comparable to those applied for other specialised journals. These papers are from 21 different countries.
Download or read book SCCS Opinion on Fragrance Allergens in Cosmetic Products written by Union européenne. Scientific Committee on Consumer Safety and published by . This book was released on 2012 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Name Reactions written by Jie Jack Li and published by Springer Science & Business Media. This book was released on 2010-03-14 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book differs from others on name reactions in organic chemistry by focusing on their mechanisms. It covers over 300 classical as well as contemporary name reactions. Biographical sketches for the chemists who discovered or developed those name reactions have been included. Each reaction is delineated by its detailed step-by-step, electron-pushing mechanism, supplemented with the original and the latest references, especially review articles. This book contains major improvements over the previous edition and the subject index is significantly expanded.
Download or read book Name Reactions written by Jie Jack Li and published by Springer Science & Business Media. This book was released on 2014-01-30 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this fifth edition of Jack Jie Li's seminal "Name Reactions", the author has added twenty-seven new name reactions to reflect the recent advances in organic chemistry. As in previous editions, each reaction is delineated by its detailed step-by-step, electron-pushing mechanism and supplemented with the original and the latest references, especially from review articles. Now with addition of many synthetic applications, this book is not only an indispensable resource for advanced undergraduate and graduate students, but is also a good reference book for all organic chemists in both industry and academia. Unlike other books on name reactions in organic chemistry, Name Reactions, A Collection of Detailed Reaction Mechanisms and Synthetic Applications focuses on the reaction mechanisms. It covers over 320 classical as well as contemporary name reactions.
Download or read book Comprehensive and Molecular Phytopathology written by Yuri Dyakov and published by Elsevier. This book was released on 2007-01-09 with total page 497 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a collection of information on successive steps of molecular ‘dialogue’ between plants and pathogens. It additionally presents data that reflects intrinsic logic of plant-parasite interactions. New findings discussed include: host and non-host resistance, specific and nonspecific elicitors, elicitors and suppressors, and plant and animal immunity. This book enables the reader to understand how to promote or prevent disease development, and allows them to systematize their own ideas of plant-pathogen interactions. * Offers a more extensive scope of the problem as compared to other books in the market* Presents data to allow consideration of host-parasite relationships in dynamics and reveals interrelations between pathogenicity and resistance factors* Discusses beneficial plant-microbe interactions and practical aspects of molecular investigations of plant-parasite relationships* Compares historical study of common and specific features of plant immunity with animal immunity
Download or read book Pharmacognosy And Pharmacobiotechnology written by Ashutosh Kar and published by New Age International. This book was released on 2003 with total page 908 pages. Available in PDF, EPUB and Kindle. Book excerpt:
