Oxocarbenium Ion Cyclizations for C-Branched Cyclitols:Synthesis of a Relay Intermediate for Fumagillin Analogues

摘要

A highly stereoselective oxocarbenium ion-alkene cyclization for synthesis of C-branched cylitols is described.This methodology was applied to 10S,a potentially versatile intermediate for side-chain analogues of the antiangiogenic agent fumagillin.Compound 10S was subsequently converted to diene 5.Because racemic 5 has been converted to racemic fumagillin,this synthesis of 5 constitutes a formal synthesis of the natural product.