Transition-Metal-Free Synthesis of Phenanthridinones through Visible-Light-Driven Oxidative C-H Amidation

The treatment of N-aryl biphenylcarboxamide, 1-chloroanthraquinone (1-Cl-AQN) catalyst, and K2CO3 in CHCl3 under visible light irradiation affords phenanthridinone via radical cyclization. This reaction proceeds under transition-metal-free condition, room temperature, and direct C-H amidation. Mechanistic studies indicate that amidyl radical generation proceeds by visible light induced proton coupled electron transfer (PCET) from N-H bond of the amide.