Novel stereocontrolled approach to syn- and anti-oxepene-cyclogeranyl trans-fused polycyclic systems: asymmetric total synthesis of (-)-Aplysistatin, (+)-Palisadin A, (+)-Palisadin B, (+)-12-hydroxy-palisadin B, and the AB ring system of adociasulfate-2 and toxicol A

Chemistry. 2004 Aug 6;10(15):3822-35. doi: 10.1002/chem.200400407.

Abstract

A new stereocontrolled method for the formation of trans-anti cyclogeranyl-oxepene systems is described. The demanding stereochemistry is secured by stereoselective coupling of a cyclogeranyl tertiary alcohol with a 1,2-unsymmetrically substituted epoxide, while the formation of the highly strained oxepene is achieved employing ring-closing metathesis. Since the stereochemistry of the trans-fused 6,7-ring system is determined by the epoxide, the method also allows the construction of trans-syn 6,7-ring systems. This approach leads to the synthesis of the AB fragment of Adociasulfate-2 and Toxicol A, for the first time. The flexibility and efficiency of the presented strategy is demonstrated by the total asymmetric synthesis of (-)-Aplysistatin, (+)-Palisadin A, (+)-12-hydroxy-Palisadin B, and (+)-Palisadin B, employing two similar key intermediates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cyclization
  • Epoxy Compounds / chemistry*
  • Models, Molecular
  • Molecular Conformation
  • Molecular Structure
  • Oxepins / chemical synthesis*
  • Sesquiterpenes / chemical synthesis*
  • Stereoisomerism
  • Structure-Activity Relationship
  • Sulfuric Acid Esters / chemical synthesis*

Substances

  • Epoxy Compounds
  • Oxepins
  • Sesquiterpenes
  • Sulfuric Acid Esters
  • adociasulfate-2
  • aplysistatin