Unified Total Synthesis of 3-epi-Ryanodol, Cinnzeylanol, CinncassiolsA and B, and Structural Revision of Natural Ryanodol and Cinnacasol

Ryanodane diterpenoids structurally share an extremely complex fused ring system, but differ in the substitution patterns of the hydroxy groups. Since these congeners exhibit various biologically important functions, their efficient chemical constructions have been greatly anticipated. We previously...

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Published inAngewandte Chemie Vol. 128; no. 7; pp. 2539 - 2543
Main Authors Koshimizu, Masaki, Nagatomo, Masanori, Inoue, Masayuki
Format Journal Article
LanguageEnglish
German
Published Weinheim Wiley Subscription Services, Inc 12.02.2016
Subjects
Assembly
Chemical synthesis
Chemistry
Congeners
Construction
Diterpenes
Oxygenated
Ryanodine
Synthesis
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Summary:Ryanodane diterpenoids structurally share an extremely complex fused ring system, but differ in the substitution patterns of the hydroxy groups. Since these congeners exhibit various biologically important functions, their efficient chemical constructions have been greatly anticipated. We previously accomplished the total synthesis of ryanodine (1) using pentacycle 8 as the advanced intermediate. Here, we report the unified total syntheses of four distinct diterpenoids, 3-epi-ryanodol (3), cinnzeylanol (4), cinncassiols B (5), and A (6), from 8, all within 10 steps. A series of highly optimized chemo- and stereoselective reactions and protecting-group manipulations enabled assembly of the densely oxygenated structures of 3-6. Furthermore, the present synthetic studies established the C13S stereochemisty of 5-7 and revised the proposed structures of natural ryanodol (2) and cinnacasol (7) to be those of 3 and 6, respectively.
Bibliography:ObjectType-Article-1
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ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201511116