Convergent, Stereoselective Synthesis of the GHIJ Fragment of Brevetoxin A

A stereoselective synthesis of the GHIJ fragment of brevetoxin A utilizing a convergent assembly strategy is described. Glycolate alkylation, ring-closing metathesis, and Hosomi−Sakurai reactions were central operations in the construction of the G ring and J ring subunits, which were united through a Horner−Wadsworth−Emmons coupling. Subsequent dehydrative cyclization produced an endocyclic enol ether that was further elaborated to the tetracyclic GHIJ fragment of brevetoxin A.