Conversion of Bicyclo[2.2.2]octane Systems into Tricyclo[3.2.1.0^2,7]octanes: A Third Synthesis of The Diterpenoid Trachylobane

Abstract

The cyclization of bicyclooctane systems to tricyclooctane systems is discussed with particular reference to stereochemical aspects as encountered during the total syntheses of ishwarane and trachylobane. Of special interest are the homoallylic cyclizations. A third, convenient synthesis of trachylobane via a reductive homoallylic cyclization is reported.