Synthesis of the necine base (−)-supinidine from (S )-glutamic acid

Abstract

A route is described towards the pyrrolizidine nucleus from derivatives of 5-acetylpyrrolidin-2-one using an intramolecular Wittig reaction with vinylphosphonium salts. The acetoxy ketone 15, derived from (S)-N-benzyloxycarbonylpyroglutamic acid, affords 16, a known precursor of (−)-supinidine.