Ethyl 4,4-dimethyl pyroglutamate (DMPG): a chiral auxiliary in cyclopropanation and carbonyl group activator

Abstract

Reaction of ethyl (S)-N -trans-2-butenoyl-4,4-dimethyl pyroglutamate with ethyl (dimethylsulfuranylidene) acetate (EDSA) or with Trost´s ylide gave rise to stereoselective cyclopropanation, promoted by the chiral auxiliary (S)-ethyl 4,4-dimethyl pyroglutamate (DMPG), which can easily be removed from the highly functionalised cyclopropanated products using various nucleophiles.