Palladium-Catalyzed Solvent-Controlled Selective Synthesis of Acyl Isoureas and Imides from Amides, Isocyanides, Alcohols and Carboxylates

A highly selective synthesis of acyl isoureas and imides from readily accessible amides, isocyanides, alcohols and carboxylates based on reaction solvent selection is described. In the presence of a catalytic amount of [1,1 '-bis(diphenylphosphino)ferrocene]dichloropalladium(II) and cupric acetate, treatment of amides and isocyanides in alcohols at 60 degrees C provided acyl isoureas in high yields. Interestingly, when other solvents such as acetonitrile was used instead of alcohols, imides were exclusively produced in good to excellent yields via direct N-acylation of amides with carboxylates as the acyl sources. This protocol offers an attractive alternative approach toward isoureas and imides.