Enantioselective Conjugate Addition of N-Heterocycles to α,β-Enones Mediated by Diarylprolinols

Enantioselective conjugate addition of benzotriazole to α,β-enones catalyzed by prolinol derivatives with moderate yields and enantioselectivities was reported. Studies of stereoelectronic effects of the catalyst showed that the transition state could be of a hydrogen bonding activation mode, and fine tuning of the substituents on the aryl moiety of the catalyst is important for the reaction stereoselectivities.