CaI2-Catalyzed Direct Transformation of N-Alloc-, N-Troc-, and N-Cbz-Protected Amines to Asymmetrical Ureas
A novel and facile CaI2-catalyzed direct synthesis of asymmetrical ureas from N-Alloc-, N-Troc-, and N-Cbz-protected amines is developed. In this study, efficient reaction of Alloc-, Troc-, and Cbz-carbamate with amines in the presence of catalytic CaI2 successfully generated various asymmetrical ureas. This catalytic synthetic procedure provided the desired ureas via reactions of these protected aromatic and aliphatic amines with various amines in high yields without side products. This suggests that novel direct synthesis of ureas from Alloc-, Troc-, and Cbz-carbamates can provide a promising approach for the synthesis of useful ureas.