An efficient synthesis of N-protected threo (2R,3S)-3-amino-1,2-epoxy phenylbutane

A precise and versatile method was developed for the synthesis of threo amino epoxide derivatives, which are useful intermediates for protease inhibitors. It involves the diastereoselective reduction of the carbonyl group of γ-N,N-dibenzyl amino α-hydroxy β-keto sulfide prepared from an amino acid, and its subsequent stereospecific conversion to an amino epoxide via acetoxy halogenation in high yield.