Asymmetric conjugate addition of thiols to (E)-3-crotonoyloxazolidin-2-one by iron or cobalt/pybox catalyst

The enantioselective conjugate addition of thiols to (E)-3-crotonoyloxazolidin-2-one was effectively catalyzed by the Fe(BF4)2·6H2O/(S,S)-ip-pybox catalyst, and the addition product was obtained with up to a 95% ee. Furthermore, the Co(ClO4)2·6H2O/(S,S)-ip-pybox catalyst also catalyzed the same reaction with a high enantioselectivity.