1,3-Elimination Reactions of (3,4-Epoxybutyl)stannanes. Approach to the Synthesis of Hirsutene

Article abstract of DOI:10.1021/jo00006a020

An advanced tricyclic precursor of hirsutene (3) was prepared by a 1,3-elimination reaction of spirocyclic epoxy stannane (7b).Compound 7b was synthesized efficiently from hydroxycyclohexenone 8b by conjugate addition of <(CH3)3Sn>2CuLi, Wittig methylenation, and VO(acac)2-catalyzed epoxidation.Intermediate 8b was prepared in five steps from the known enone 9 in 18percent overall yield.An improved synthesis makes compound 9 available in four efficient steps from keto ester 12.