Download or read book Toward Total Synthesis of Azaspiracid 3 and Azaspiracid 34 written by Antony Akura Okumu and published by . This book was released on 2016 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Azaspiracids are a class of marine natural products that accumulate in shellfish. Azaspiracid 1 was first reported in 1995 in the Netherlands after a poisoning incident and this led to its isolation and structure elucidation in 1998. Biological activities of azaspiracids are not fully known and further studies are necessary. They occur in scarce quantities in nature and therefore synthesis in the laboratory would facilitate these studies. There is need to examine their molecular pharmacology and to develop better means of their detection. The C1-C21 (ABCD) and C22-C40 (FGHI) fragments have been synthesized in our lab. The key reactions toward these synthesis were Nozaki-Hiyama-Kishi reaction, the Chelation controlled Mukaiyama aldol reaction, and trioxadispiroketalization under thermodynamic conditions. Earlier work in the group also involved gold-catalyzed trioxadispiroketalization. Syntheses of analogs of azaspiracids are necessary for toxicological studies, and to enable better environmental regulation. The highlight of the synthesis of the ABCD fragment of azaspiracid 34 was a Wittig olefination, selective conjugate reduction that was carried out at different stages of synthesis, and NHK coupling.

Download or read book Effort Toward the Total Synthesis of Azaspiracid 3 written by Zhigao Zhang and published by . This book was released on 2013 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: A NHK reaction to couple the C1-C21 and C22-C40 domains has also been proposed. The revised C22-C40 domain was achieved with a similar synthetic route.

Download or read book Progress Towards the Total Synthesis of Azaspiracids written by Jianyan Xu and published by . This book was released on 2006 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Total Synthesis of Azaspiracid 3 C20 epi azaspiracid 3 and Structural Definition of the Azaspiracids written by Nathaniel T. Kenton and published by . This book was released on 2018 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the work described here, the previously-accepted structure of azaspiracid-3 was synthesized for the first time and shown to be non-identical to the natural product. A series of experiments, culminating in a total synthesis of the true structure, identified the C20 stereochemistry of the natural product as being epimeric to the expected structure. Because 1H-NMR data for the C19 and C20 methine protons among all known azaspiracids are very similar, a general stereochemical correction at C20 for this family of molecules is necessary. 5.5 mg of purified, natural azaspiracid-3 was produced.

Download or read book Part I Total Synthesis of Azaspiracid 3 written by Eriketi Loizidou and published by . This book was released on 2006 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies Toward the Total Synthesis of Azaspiracid 1 written by Brian Kenneth Raymer and published by . This book was released on 2004 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Towards the Total Synthesis of Azaspiracid 3 written by Ding Yue and published by . This book was released on 2010 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: A novel tert-butyl lithium mediated ring closure strategy was described in the synthesis of the carbon skeleton of azaspiracid-3. This novel strategy disconnected the compound into two fragments. The synthesis of both fragments was described. Because of reactivity issues, some protecting group must be altered before the coupling could be achieved. After coupling, the key ring closure proceeded as expected. Some purification techniques were needed in order to achieve the total synthesis of azaspiracid-3.

Download or read book Studies Toward the Total Synthesis of Azaspiracid 1 written by Damien L. Kuiper and published by . This book was released on 2010 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: Azaspiracid has generated an enormous amount of scientific interest in the fourteen years since its initial discovery. The structure contains a 6,5,6 bis-spiroketal, a [3.3.1] bicyclic ketal and a 6,5-spiroaminal linkage as key moieties. With 9 rings, 20 stereocenters and three alkenes, the azaspiracid immediately attracted the interest of the synthetic community. To date, two syntheses have been reported by the Nicolaou and Evans laboratories. An initial route to the C13-C19 aldehyde was plagued by a problematic 1,2 silyl migration. An improved route to the C13-C19 aldehyde was developed based on a modified protecting group strategy utilizing a PMP ketal. The improvements in the synthesis led to facile production of 250 mg of the key transoidal ABC ring bisspiroketal. This second generation route dramatically improved the efficiency of our synthesis, with the overall yield for the C13-C19 aldehyde increasing from 2% to 15%, which allowed the synthesis of over 250 mg the bisspiroketal. An optimized route to the FGHI spiroaminal was developed. A unique equilibration method for the construction of the anomerically-stabilized spiroaminal was discovered. After cleavage of the Cbz carbamate, an in situ tautomerization provided the desired doubly anomeric FGHI spiroaminal subunit. This transformed a total synthesis of FGHI spiroaminal into a process which could easily produce gram quantities of advanced intermediates requisite for the synthesis of azaspiracid. With an optimized synthesis of the FGHI ring system complete, a host of routes were investigated for the coupling of the C26-C40 fragment and C20-C25 fragment was developed. The C25-C26 bond was formed via an aldol condensation between FGHI methyl ester and the C20-C26 aldehyde. A novel TAS-F-mediated elimination was developed to provide the C26-C44 olefin. The Horner-Wadsworth-Emmons coupling of the C4-C19 lactol and C20-C40 ketophosphonate furnished the contiguous C4-C45 framework of azaspiracid-1. Davis oxidation of C20 provided the requisite oxidation state. The only challenges remaining are desilylation at C25 and cross metathesis at C4 to complete a formal synthesis of azaspiracid.

Download or read book Synthesis of the ABCD Domain of the Azaspiracids written by Feng Zhou and published by . This book was released on 2010 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis describes synthetic efforts toward the total synthesis of the azaspiracid marine toxins. The investigation here focuses on the synthesis of the ABCD bis-spiroketal domain. Several different approaches have been developed. One features a gold catalyzed spiroketalization, which used a triple bond as an oxidation-state equivalent of a ketone to establish a spiroketal structure. In the D-ring synthesis, a Co(modp)2 (modp: 1-mophorlinocarbamoyl-4,4-dimethyl-1,3-pentadione) catalyzed oxyetherification was applied. In the recently revised synthetic route, the D-ring was constructed through a tandem asymmetric epoxidation and epoxide opening process.

Download or read book Synthesis of the C21 C40 Domain of Azaspiracid 3 written by Shuang Liang and published by . This book was released on 2007 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phycotoxins written by Luis M. Botana and published by John Wiley & Sons. This book was released on 2008-02-28 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phycotoxins: Chemistry and Biochemistry presents the most updated information available on phycotoxins. Major emphases are given to chemistry and biochemistry, while minor emphases are given to the aspects of origin, toxicology, or analytical methodology. The book discusses 16 phycotoxins, 7 on those affecting the nervous systems, 4 affecting other body systems; and 4 with undefined targets. An alphabetical listing of toxins presented includes: Azaspiracids; Brevetoxins; Cyanobacterial toxins; Domoic acid; Gambierols; Gymnodimines, prorocentrolides, spirolides, pinnatoxins and cyclic imines in general; Maitotoxin; Okadaic acid and dinophysistoxins; Palytoxins and ostreocins; Pectenotoxins; Polycavernosides; and Yessotoxins. In addition, several mechanistic aspects of newer or emerging toxins are covered such as amphidinols or gymnocine. Information presented and coverage of each toxin follows the following distribution: background and toxicology (10%); chemistry, biochemistry and metabolism (75%); mechanism of action (10%); and analytical methodology (5%). The detailed information on chemistry in Phycotoxins: Chemistry and Biochemistry provides investigators, regulators, food technologists and toxicologists an updated basis on which research in other areas such as toxicology, mechanism of action, analytical methodology and pharmacology can be successfully developed and expanded.

Download or read book I Synthetic Studies Toward Pandamarilactone 1 II Synthetic Efforts Toward the Synthesis of Azaspiracid Synthesis of the C27 C40 Polycyclic Domain written by Josep Aiguadé Bosch and published by . This book was released on 2001 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Index Medicus written by and published by . This book was released on 2001 with total page 1336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.

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 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 Organic Chemistry written by Pierre Vogel and published by John Wiley & Sons. This book was released on 2019-07-30 with total page 1382 pages. Available in PDF, EPUB and Kindle. Book excerpt: The know-how about reactivity, reaction mechanisms, thermodynamics and other basics in physical organic chemistry is the key for successful organic reactions. This textbook presents comprehensively this knowledge to the student and to the researcher, too. Includes Q&As.