Aziridine sulfides and disulfides as catalysts for the enantioselective addition of diethylzinc to aldehydes.

Chiral aziridine sulfides and disulfides were synthesized from readily available and inexpensive R-cysteine by a Mitsunobu reaction; their application in the addition of diethylzinc to aldehydes provides secondary alcohols with up to 99% ee and S-configuration.