Studies on Organophosphorus Catalyzed C(SP³)–H Amination for the Synthesis of Benzimidazoles

Abstract

A PIII/PV=O-catalyzed C(sp³)–H amination has been realized for (dihydro)benzimidazole synthesis. This work reports: (1) optimization of organophosphorus-catalyzed C(sp³)–H functionalization; (2) scope studies to benzimidazoles by in situ oxidation of the corresponding dihydrobenzimidazole; and (3) insight into the reaction mechanism through in situ spectroscopic monitoring under catalytic conditions and Hammett linear free energy relationship studies. The synthetic method and mechanistic information provide insight into design principles for the expansion of C(sp³)–H functionalization reactions through PIII/PV=O O-atom transfer reactivity.