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 ³¹P NMR studies, activation of HCl appears to proceed via quantitative protonation of the catalyst to afford a phosphonium chloride complex.