Basicity-Tuned Selectivity: Synthesis of Benzimidazolone and Benzodiazepine from N-Alkyl-N-(2-(pyridin-2-ylamino)-phenyl)formamides

A base-controlled strategy for the selective preparation of benzimidazolone and pyrido-benzodiazepine derivatives was developed. The N-alkyl-N-(2-(pyridin-2-ylamino)phenyl)formamides underwent selective coupling to synthesize a series of benzimidazolones when NaOAc was used as bases and employed K2S2O8 as oxidants. By changing bases to NaHCO3, a series of benzodiazepines was obtained. The possible reaction mechanism was proposed based on the radical-trapping experiments. The applicability of this protocol is demonstrated by scale-up experiments and the functionalization of benzodiazepine products.