Multicomponent Reaction of 2-aminobenzimidazole, Arylglyoxals, and 1,3-cyclohexanedione

Three-component reactions of 2-aminobenzimidazole with arylglyoxals and 1,3-cyclohexanedione have been studied under conventional heating and microwave irradiation. Different product types including the Michael adduct and fused heterocyclic systems were obtained. Conditions for the selective formation of 12-aroylbenzimidazo[2,1- b ]quinazolin-1(2 H )-ones and 3-oxo-2-(2-aryl-1 H -imidazo[1,2- a ]-benzimidazol-9-ium-3-yl)cyclohex-1-enolates have been determined. The structures of all compound types were established by an X-ray diffraction study.