Bifunctional Asymmetric Catalysis with Hydrogen Chloride: Enantioselective Ring-Opening of Aziridines Catalyzed by a Phosphinothiourea.

Ring-opening of aziridines with hydrogen chloride to form β-chloroamine derivatives is catalyzed by a chiral phosphinothiourea derivative in high yields and with high enantioselectivities. On the basis of (31)P NMR studies, activation of HCl appears to proceed via quantitative protonation of the catalyst to afford a phosphonium chloride complex.