Author: Michaela C. Vertorano
Publisher:
ISBN:
Category : Alkaloids
Languages : en
Pages : 69

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Book Description

Author: Sarah Elizabeth House
Publisher:
ISBN:
Category :
Languages : en
Pages : 370

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Book Description
A unified approach to the total synthesis of Lycopodium alkaloids belonging to the miscellaneous class has been developed, wherein a single tetracyclic amine is employed as a common intermediate in synthetic studies toward several alkaloids. An overview of Lycopodium alkaloids is presented, including their structural classification, isolation and biological activity. The biosynthesis of alkaloids in the miscellaneous group is discussed in depth. A summary of previous synthetic work focusing on miscellaneous Lycopodium alkaloids is presented, including total syntheses of luciduline, lyconadins A and B and nankakurines A and B.A model study of spirolucidine is discussed. A biomimetic route to access spirolucidine and nankakurine B has been investigated. In this study, a tetracyclic amine that is a key intermedite in the total synthesis of lyconadin A previously developed in our laboratory is elaborated into a tertiary alcohol that mimics the proposed biosynthetic precursor of nankakurine B.A biomimetic ring-contractive [alpha]-hydroxyimine rearrangement to generate nankakurine B has been extensively investigated and found to be disfavored. The conversion of a tricyclic ketone (first synthesized en route to lyconadin A) to the tetracyclic core of serratezomine D has been investigated. The core of this molecule was inaccessible via methods employed in the studies toward lyconadin A. The total synthesis of 1'-epi-dihydrolycolucine from the key common tetracyclic amine intermediate has been achieved. Studies toward the synthesis of serratezomine E served as a platform to develop this method and to determine the stereochemical outcome of this reaction.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Spirolucidine is a complex alkaloid isolated from the club moss Lycopodium lucidulum. A three fragment convergent plan for the title compound was envisioned, with each fragment being derived from a chiral N-acyl-2,3-dihydro-4-pyridone. The synthesis of the bicyclic enecarbamate referred to as zone C was investigated. The first effort centered on a tandem intramolecular Diels-Alder reaction/retro Mannich ring opening reaction to set the key stereogenic centers within zone C.A second strategy aimed to ring open the tricyclic adduct which arises from the Diels-Alder reaction through an E1cB mechanism. Finally, a third attempt was made to utilize chirality transfer as a means to implement the necessary stereochemical elements of the bicyclic scaffold. The convergent union of the key fragments of spirolucidine was modeled on a simple substrate. The directed lithiation of N-Boc-dihydropyridines was utilized to prepare model 2,5,6-trisubstituted dihydropyridones of a general type needed for the completion of the spirolucidine synthesis.

Author: Kenneth Piers
Publisher:
ISBN:
Category : Alkaloids
Languages : en
Pages : 0

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Book Description
The transformation of lycopodine into annofoline via an unsaturated amido acetate has been carried out. This transformation is of biogenetic interest since lycopodine has been postulated to be the central intermediate in the biosynthesis of the Lycopodium alkaloids. The transformation of the unsaturated amido acetate obtained above into lycopodine has been carried out. This transformation is of potential use in the total synthesis of lycopodine since it provides a synthetic method of controlling the stereochemistry of the C-15 methyl group. The total synthesis of the cernuine ring skeleton has been achieved thus confirming the structural assignment made for the alkaloids cernuine and lycocernuine. The total synthesis was also useful in confirming the stereochemistry of the naturally occuring compounds .

Author: Mrinmoy Saha
Publisher:
ISBN:
Category : Alkaloids
Languages : en
Pages : 451

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Book Description
Lycopodium alkaloids have shown widespread and noteworthy biological activity, consisting of over 250 known natural products. Moreover, their structural complexity and diversity have attracted considerable attention from numerous laboratories including our own. Recently, we have developed a unified approach that would provides access to numerous, previously unprepared C10-functionalized lycopodium alkaloids. The first enantioselective total syntheses of all C10-hydroxy lycopodium alkaloids have been accomplished. We have also made a significant progress towards himeradine A and other C10-functionlyzed pentacyclic lycopodium alkaloids. Key steps in the synthetic sequence towards C10-hydroxy lycopodium alkaloids include construction of six-membered ring using an organocatalyzed intramolecular Michael reaction, formation of tricyclic skeleton using a conformationally accelerated Mannich reaction and a tandem Oppenauer oxidation / aldol condensation cascade reaction to form the tetracyclic skeleton of the natural products. A proline sulfonamide catalyst has been explored and expanded for the intramolecular Michael reaction for the construction of common six-membered ring for all the C10-functionalized lycopodium alkaloids. During our endeavor towards the sis- membered ring formation it was observed that rate of the Michael reaction and conversion to product increases dramatically in presence of the proline sulfonamide catalyst. The effect of C10 stereochemistry (both R and S) was also explored in the Michael reaction and (R)-C10-epimer proved to give better diastereoselectivity during the process. A conformationally accelerated, intramolecular Mannich reaction route was utilized to the tricyclic skeleton of all C10-hydroxy lycopodium alkaloids to construct C4- C13. During the Mannich reaction the effect of C10 stereochemistry was explored as well and it was found that C4-C13 bond could only be formed with (R)-C10-epimer. In addition, protecting group on C10 alcohol has significant effect on the intramolecular Mannich reaction. We have accomplished the first enantioselective total synthesis of 10-hydroxylycopodine, deacetylpaniculine and paniculine. During our endeavor towards these natural products we have utilized an Oppenauer oxidation/aldol condensation cascade reaction to form the tetracyclic skeleton from the tricyclic intermediate. We have reported the first fully characterized NMR data for 10-hydroxylycopodine and optical rotation data for all the C10-hydroxy lycopodium alkaloids. Key aspects towards the C10-functionalyzed lycopodium alkaloids are Mander's reagent -mediated one carbon homologation, a tandem sulfone rearrangement / intramolecular Mannich cyclization to form the key tricyclic skeleton and synthesis of the advanced C10-alcohol intermediate towards the western portion of himeradine A. Additionally, the western portion of himeradine A will serve as the common intermediate towards related pentacyclic C10-functionalyzed lycopodium alkaloids. During the synthesis of the tricyclic C10-alcohol, several routes have been explored to functionalize the C4 center and finally the Mander's reagent strategy successfully installed the C3 ester. A significant tricyclic skeleton towards the pentacyclic C10-functionalyzed lycopodium alkaloids was achieved through utilization of a tandem 1,3-sulfone rearrangement/intramolecular Mannich reaction as the key steps. Polymer supported PPh3 was utilized to improve the yield of the Aza-Wittig / Mannich reaction sequence. We have discovered that the incorporation of the methyl-protecting group on C5-enol and reduction of the C3 ester to alcohol was necessary in order to successfully facilitate the C14-desulfurization.

Author: Hans-Joachim Knoelker
Publisher: Springer Science & Business Media
ISBN: 3642255280
Category : Science
Languages : en
Pages : 268

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Book Description
Lycopodium Alkaloids: Isolation and Asymmetric Synthesis, by Mariko Kitajima and Hiromitsu Takayama.- Synthesis of Morphine Alkaloids and Derivatives, by Uwe Rinner and Tomas Hudlicky.- Indole Prenylation in Alkaloid Synthesis, by Thomas Lindel, Nils Marsch and Santosh Kumar Adla.- Marine Pyrroloiminoquinone Alkaloids, by Yasuyuki Kita and Hiromichi Fujioka.- Synthetic Studies on Amaryllidaceae and Other Terrestrially Derived Alkaloids, by Martin G. Banwell, Nadia Yuqian Gao, Brett D. Schwartz and Lorenzo V. White.- Synthesis of Pyrrole and Carbazole Alkaloids, by Ingmar Bauer and Hans-Joachim Knölker.-

Author: E.J. Corey
Publisher: Рипол Классик
ISBN: 5885010811
Category : Science
Languages : en
Pages : 447

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Book Description

Author: Montserrat Diéguez
Publisher: John Wiley & Sons
ISBN: 3527804072
Category : Technology & Engineering
Languages : en
Pages : 431

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Book Description
An important reference for researchers in the field of metal-enzyme hybrid catalysis Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a comprehensive review of the most current strategies, developed over recent decades, for the design, synthesis, and optimization of these hybrid catalysts as well as material about their application. The contributors—noted experts in the field—present information on the preparation, characterization, and optimization of artificial metalloenzymes in a timely and authoritative manner. The authors present a thorough examination of this interesting new platform for catalysis that combines the excellent selective recognition/binding properties of enzymes with transition metal catalysts. The text includes information on the various applications of metal-enzyme hybrid catalysts for novel reactions, offers insights into the latest advances in the field, and contains an informative perspective on the future: Explores the development of artificial metalloenzymes, the modern and strongly evolving research field on the verge of industrial application Contains a comprehensive reference to the research area of metal-enzyme hybrid catalysis that has experienced tremendous growth in recent years Includes contributions from leading researchers in the field Shows how this new catalysis combines the selective recognition/binding properties of enzymes with transition metal catalysts Written for catalytic chemists, bioinorganic chemists, biochemists, and organic chemists, Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a unique reference to the fundamentals, concepts, applications, and the most recent developments for more efficient and sustainable synthesis.

Author: Jie Jack Li
Publisher: Springer Science & Business Media
ISBN: 3642340652
Category : Science
Languages : en
Pages : 292

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Book Description
'Total Synthesis of Natural Products' is written and edited by some of today's leaders in organic chemistry. Eleven chapters cover a range of natural products, from steroids to alkaloids. Each chapter contains an introduction to the natural product in question, descriptions of its biological and pharmacological properties and outlines of total synthesis procedures already carried out. Particular emphasis is placed on novel methodologies developed by the respective authors and their research groups. This text is ideal for graduate and advanced undergraduate students, as well as organic chemists in academia and industry.

Author: Navjeet Kaur
Publisher: Elsevier
ISBN: 0128202831
Category : Science
Languages : en
Pages : 526

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Book Description
Metal and Nonmetal Assisted Synthesis of Six-Membered Heterocycles provides a useful guide to key approaches being explored in this area. The volume highlights synthetic approaches and catalytic options that facilitate the construction of multiple substituted molecules under mild conditions from easily available starting substrates. Drawing on the experience of its expert author, the book is a useful guide on the key approaches being explored in this area. Following a user-friendly structure based on specific six-membered heterocycle ring groups, this volume highlights synthetic approaches and catalytic options that facilitate the construction of multiple substituted molecules under mild conditions from easily available starting substrates. Highlights new methodologies for the synthesis of different six-membered heterocycles Provides an up-to-date overview of this fast-moving field with an easy-to-use structure Includes novel approaches used in the study and application of catalysts in synthetic organic reactions