Aerobic C(sp3)–H oxidation and oxygenation of quaternarized quinolines and pyridines by visible-light-induced photocatalysis

Abstract

Herein, we report on visible-light-induced photocatalysis that enables aerobic oxidation and oxygenation of quaternarized N-heterocycles. Complete oxidation of methyl group and partial oxidation of methylene have been selectively realized. Hence, two kinds of oxygenation products (>60 new products) including carboxylate inner salts and alcohols have been accessed under mild aerobic conditions. The broad compatibility of useful functional groups in this synthetic protocol has been established. Notably, in the case of alcohol isolation recrystallization was adopted to afford high yields of products. Mechanistic studies support an oxidation process initiated by singlet oxygen for both oxygenation reactions.