Palladium(II)-Catalyzed Sequential C-H Arylation/Aerobic Oxidative C-H Amination: One-Pot Synthesis of Benzimidazole-Fused Phenanthridines from 2-Arylbenzimidazoles and Aryl Halides

Starting from 2-arylbenzimidazoles and aryl halides, an efficient palladium-based catalytic method for the synthesis of benzimidazole-fused phenanthridines has been developed. This reaction sequence comprises intermolecular C-H arylation and intramolecular aerobic oxidative C-H amination, involving the rupture of two C-H bonds, one C-X bond, and one N-H bond in one pot. The Pd-II-Pd-IV-Pd-II and Pd-II-Pd-0-Pd-II catalytic cycles work together under the reported conditions to generate phenanthridines with diverse substituents.