We herein report a potent photocatalytic system for arene C-H amination utilizing an isoquinolinium photooxidant. The key to the process involves in situ protonation of neutral isoquinoline precatalyst IQ1. Resulting isoquinolinium IQ1•H+ exhibits a high excited-state reduction potential (+2.33 V vs SCE), enabling single-electron-transfer oxidation of inert arenes. The optimized reaction system demonstrates a broad scope, including electronically neutral arenes and various pharmaceutical small molecules with azoles and pyridines.
Wakabayashi et al. (Sun,) studied this question.