Regiospecific ring-opening reactions of aziridines bearing an α,β-unsaturated ester group with trifluoroacetic acid or methanesulfonic acid: application to the stereoselective synthesis of (E)-alkene dipeptide isosteres

Abstract

Reaction of N-(2,4,6-trimethylphenylsulfonyl)-γ,δ-cis- or -trans-γ,δ-epimino (E)-α,β-enoates with acids such as TFA or methanesulfonic acid (MSA) affords the stereo- and regio-selective ring-opened products in high yields, and subsequent treatment of resulting δ-aminated γ-mesyloxyα,β-enoates with organocopper reagents yields diastereoisomerically pure (E)-alkene dipeptide isosteres.