A Very Rapid Stereocontrolled Entry to Highly Functionalized [5-8-5] Ring Systems Using the Saegusa Reaction

Abstract

A highly functionalized dicyclopenta[a,d]cyclooctanone product, representing the basic [5-8-5] skeleton found in natural products such as the ophiobolins and fusicoccins, was prepared in only four synthetic steps from a readily available bridged ketone. The highly stereoselective sequence involves use of the Saegusa ring-expansion protocol to effect initial ring expansion−cyclization and a subsequent radical cyclization using TolSO2SePh.