Synthesis of substituted urea or benzimidazolone using 1,1’-carbonyldiimidazole and substituted anilines

Abstract

1,1’-carbonyldiimidazole (CDI) is a versatile reagent that can be used for synthesizing a variety of organic compounds containing carbonyl functional groups. The reactivity of CDI with two ortho-substituted anilines was tested and characterized with analytic techniques such as NMR, IR, and ESI-MS. A reaction of CDI with two equivalents of di-substituted aniline (N1,N1-diethylbenzene-1,2-diamine) formed a urea compound, 1,3-bis(2-(diethylamino)phenyl)urea (1). On the other hand, a reaction with one equivalent of mono-substituted aniline (tert-butyl (2-aminophenyl)carbamate) formed a substituted benzimidazolone, tert-butyl 2-oxo-2,3-dihydro-1H-benzo[d]imidazole-1-carboxylate (2). These results demonstrated that a singly substituted aniline prefers an intramolecular ring formation while an N,N-doubly-substituted aniline prefers a urea formation.