The Synthesis of (S)-3-Acetylthio-2-benzylpropionic Acid from (Z)-2-Chloromethyl-3-phenylprop-2-enoic Acid by Asymmetric Hydrogenation: a Chiral Building Block of an Enkephalinase Inhibitor

Abstract

(S)-2-Benzyl-3-chloropropionic acid (7) was synthesized from (Z)-2-(chloromethyl)-3-phenylprop-2-enoic acid (5) by asymmetric hydrogenation with a ruthenium 2,2′-bis(di-p-tolylphosphino)-1,1′-binaphthyl complex in the presence of triethylamine. Acetylthiolation then gave 3-acetylthio-2-benzylpropionic acid (2), a subunit of the enkephalinase inhibitor thiorphan (1).