Convenient route to enantiopure substituted butyrolactones: application in a formal synthesis of both enantiomers of enterolactone

A simple route for the synthesis of enantiopure substituted γ-butyrolactones involving a highly diastereoselective alkylation of an enantiomerically pure substituted latent succinate ester is described. This route provides entry into both enantiomers of 3,4-disubstituted butyrolactones from a single enantiomer, 2,3-di-O-cyclohexylidine-R-(+)-glyceraldehyde. The synthetic potential of this methodology has been demonstrated by a formal synthesis of both enantiomers of enterolactone.