Synthetic studies towards naturally occurring sesquiterpene capillosanane V: construction of a fully functionalized cycloheptane core through an intramolecular Reformatsky reaction

Abstract

We herein disclose the synthesis of a bicyclo [5,1,0]-octane ring system consisting of a cycloheptane core fused with a cyclopropane unit of naturally occurring sesquiterpene capillosanane V. Initially, an unsuccessful RCM reaction of a properly functionalized bis-olefinic precursor was attempted. Finally, an intramolecular Reformatsky reaction was employed to construct the cycloheptane core present in the target structure. The α-bromo-ester precursor for the Reformatsky reaction was assembled through an aldehyde homologation with ketene dithioacetal.