Catalytic aerobic generation of acyliminium ions through electron-transfer-mediated carbon-carbon bond activation

Homobenzylic amides and carbamates, upon single-electron oxidation, undergo mesolytic cleavage reactions to form acyliminium ions. Appending nucleophilic groups to these substrates results in cyclization reactions to form N-acylaminals. The N-methylquinolinium ion that serves as the photooxidant in these reactions can function as a catalyst when dioxygen is introduced into these reactions, representing a unique method for effecting catalytic, aerobic oxidations. Herein we present a full account of our studies on catalytic aerobic electron-transfer-initiated cyclization reactions of homobenzylic amides and carbamates, with particular emphasis on the roles of the amide group, the nucleophilic group, and the functionality in the tether in promoting efficient ring constructions and altering reaction mechanisms.