Nucleophilic Addition Catalyzed by Novel Multi-Functional Thiourea Derivatives

Abstract

We have found that some thioureas efficiently promoted nucleophilic addition of TMSCN and ketene silyl acetals to nitrones, giving the corresponding hydroxyamines in good yield. In addition, we synthesized novel chiral thiourea derivatives with 2-dialkylamino-cylclohexyl groups. This type of thioureas could be used as non-metallic bifunctional organocatalysts. Indeed, these thioureas catalyzed asymmetric Michael reaction of malonates to nitroolefins and afforded the desired Michael adducts with high enantioselectivity (up to 93% ee).