Progress Towards an Alternative Total Synthesis of the Marine Macrolide Amphidinolide J PDF Download
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Author: Christopher Michael Verdon
Publisher:
ISBN:
Category : Drugs
Languages : en
Pages : 374
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Author: Christopher Michael Verdon
Publisher:
ISBN:
Category : Drugs
Languages : en
Pages : 374
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Author: Subham Mahapatra
Publisher:
ISBN:
Category : Macrolide antibiotics
Languages : en
Pages : 639
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Book Description
More than 30 members of the diverse amphidinolide family of biologically active macrolides have been isolated over last three decades. From this family, amphidinolides C and F stand among the most complex and densely functionalized affiliates. Recently, we have accomplished the first total synthesis of amphidinolide F. The all-carbon framework of amphidinolide C has been synthesized. During endeavor toward the total syntheses of amphidinolides F / C, we have uncovered a "hidden symmetry element" present in the northern and southern domains of amphidinolides F / C. The southern C1-C and northern C1-C25 tetrahydrofuran segments were derived from a common intermediate. A scalable silver-catalyzed isomerization / cyclization on propargyl-benzoate / diol furnished the common intermediate in multigram quantity. The common intermediate provided access to over half of carbon backbone of the macrocycle as well as majority of stereochemistry present in amphidinolides F / C. Two strategically different techniques have been developed for the C9-C11 diene preparation. A metal-catalyst free Weinreb amide-vinyl lithium coupling / methylenation sequence furnished the diene motif. Alternately, diastereoselective addition of a dienyl iodide derived 2-lithio-1,3-diene species to an [alpha]-oxy aldehyde installed the C9-C11 diene and secured the C8 stereochemistry in single operation. The dienyl iodide was prepared via a regioselective hydrostannylation on an enyne. A challenging alkylation between an [alpha]-branched sulfone and an [alpha]-silyloxy iodide generated the all-carbon frameworks of amphidinolides F / C. An efficient oxidative desulfurization incorporated the carbonyl moiety at C15. The protecting group on C18 alcohol was found to have significant effect on the sulfone-iodide alkylation / oxidative desulfurization sequence. Installation of chelating ethoxyethyl ether on C18 alcohol helped the successful incorporation of C15 ketone and solved the deprotection problem in advanced stage of synthesis. A detailed analytical and computational study on proline sulfonamide-catalyzed aldol reactions has been performed. The pKa value of a proline sulfonamide catalyst was determined experimentally via NMR titration technique. Computational study revealed the origin of enhanced stereoselectivity by proline sulfonamide catalysts over parent proline. The non-classical hydrogen bonding interactions were found to be responsible for improved diastereoselectivity.
Author: William E. Brenzovich (Jr.)
Publisher:
ISBN:
Category : Antineoplastic agents
Languages : en
Pages : 916
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Author: Jesse D. Carrick
Publisher:
ISBN:
Category :
Languages : en
Pages : 170
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Author: Naga Sesha Sai Pavan Kumar Chebolu
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 0
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Book Description
Structurally complex macrolide natural products, isolated from a variety of marine and other sources, continue to provide a valuable source of targets for the synthetic chemist to embark. In this account, we provide the recent progress and pathways in the total synthesis of macrolides and discussed the synthesis of (+)-neopeltolide, aspergillide D, miyakolide and acutiphycin natural products.
Author: Andrew Frederick Nolting
Publisher:
ISBN:
Category :
Languages : en
Pages : 194
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Author: Chen Tao
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Zhanhao Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Author: Nicholas A. Morra
Publisher:
ISBN:
Category :
Languages : en
Pages :
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A second generation catalyst for the Mukaiyama oxidative cyclization for the formation of trans-THF rings is described. Co(nmp)2, displays increased stability to the reaction conditions, resulting in lower catalyst loadings, lower reaction temperatures, and significantly higher purity and yields of the products. Three procedures have been developed with this new water-soluble catalyst that greatly simplifies the post-reaction purification, making this procedure the premier method of forming trans-THF rings. This new catalyst has been applied towards the total synthesis of the potently bioactive macrocycle, Amphidinolide C. Herein we report the successful synthesis of several fragments of the natural product, and our attempts at coupling them to complete the synthesis. The C(1)-C(9) was achieved via two routes, both utilizing the highly effective oxidation catalyst Co(nmp)2 to form the methyl substituted trans-THF ring. Synthetic highlights include a regioselective Shi epoxidation, and the design and introduction of a novel Lewis acid (BF2OBn×OEt2) to facilitate a stereoselective reductive epoxide opening. The C(18)-C(34) fragment was also achieved via two routes, culminating in both the shortest (11 steps) and highest yielding (26% overall yield) approaches to this segment. Synthetic highlights of this fragment include a selective methylation of a diyne, and a highly selective alkynylation of a THF aldehyde, achieving excellent dr (>20:1) without the addition of an external chiral compound. Advanced intermediates comprising the entirety of the carbon backbone of the molecule have been synthesized, which in theory could complete the total synthesis in as few as two bond forming steps.
Author: Alexandros L. Zografos
Publisher: John Wiley & Sons
ISBN: 1118751736
Category : Science
Languages : en
Pages : 585
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Book Description
Focusing on biosynthesis, this book provides readers with approaches and methodologies for modern organic synthesis. By discussing major biosynthetic pathways and their chemical reactions, transformations, and natural products applications; it links biosynthetic mechanisms and more efficient total synthesis. • Describes four major biosynthetic pathways (acetate, mevalonate, shikimic acid, and mixed pathways and alkaloids) and their related mechanisms • Covers reactions, tactics, and strategies for chemical transformations, linking biosynthetic processes and total synthesis • Includes strategies for optimal synthetic plans and introduces a modern molecular approach to natural product synthesis and applications • Acts as a key reference for industry and academic readers looking to advance knowledge in classical total synthesis, organic synthesis, and future directions in the field
