Stereoselective Synthesis of Naturally Occurring α-Methylenebis-γ-butyrolactones: An Application of Novel Oxiranyl “Remote” Anions

Abstract
Stereospecific deprotonation of the epoxy proton at the β-position of the α,β-epoxy esters 5 and 6 yielded oxiranyl “remote” anions 7 and 8, which could then be used for alkylation. The anions 7 and 8 underwent a consecutive aldol lactonization to give, respectively, epoxy lactones 11 and 13 with high stereoselectivity. Generation of the remote anions as well as their stereoselective reactions served as a new synthetic route to the naturally occurring α-methylenebis-γ-butyrolactones, 1.