Synthetic studies toward the zoanthamine alkaloids: synthesis of the fully functionalized BC ring motif

Abstract

A synthetic approach toward lactone 20 , representing the fully functionalized BC ring motif of the zoanthamine alkaloids, has been developed and is presented herein. The challenging C9 quaternary center of 20 was installed by a Wilkinson hydrogenation of enone 17 followed by construction of an α-bromo acetal and intramolecular cyclization exclusively from the α face of the BC ring system.