Transition‐Metal‐Free Synthesis of 1,2‐diphenyl‐1H‐benzo[d] Imidazole Derivatives from N‐phenylbenzimidamides and Cyclohexanones

Abstract

A transition-metal-free strategy for the formation of 1,2-diphenyl-1H-benzo [d] imidazoles from N-phenylbenzimidamides and cyclohexanones is introduced. This is the first report on the direct synthesis of 1,2-diphenyl-1H-benzo[d] imidazoles from cyclohexanones and N-phenylbenzimidamides via iodine-promoted oxidative cyclization. Nonaromatic cyclohexanones were smoothly dehydrogenated, and acted as an aryl source using oxygen as a green oxidant. The catalytic use of iodine makes this method quite simple, more economical and convenient. Under optimized conditions, various substituted 1,2-diphenyl-1H-benzo[d] imidazoles were smoothly reacted, and the desired substituted imidazoles were generated with moderate to excellent yields.