Highly Stereoselective Formation of a Spiro Center by a 1,4-Addition/Elimination Reaction of 3,5-Difluorocyclohexa-2,5-dienones

Abstract

Spirocyclic 3,5-difluorocyclohexa-2,5-dienones possessing a triisopropylsiloxy-containing cyclic ether appendage were synthesized by oxidative dearomatization of the corresponding phenols. By group selectivity in the nucleophilic 1,4-addition/elimination reaction, highly stereoselective formation of the spiro center was successfully achieved. This reaction might provide access to total syntheses of (+)-bisdechlorogeodin and (+)-geodin with complete control of the formation of the spirocyclic structure.