Visible-Light-Induced Acridinium and Pyridine <i>N</i> -Oxide Dual Catalysis for Direct Acylation of Azauracils with Aldehydes

A visible-light-driven cross-dehydrogenative coupling of azauracils with aldehydes is described by using dual acridinium photoredox and pyridine <i>N</i>-oxide hydrogen atom transfer catalysis. This oxidant-free method generates acyl radicals under mild conditions, tolerates diverse functional groups, proceeds under air, and is scalable to gram quantities. Mechanistic studies support the selective oxidation of pyridine <i>N</i>-oxide by the photoexcited catalyst, enabling aldehyde activation. This operationally simple protocol provides a sustainable platform for the late-stage functionalization of nitrogen-rich heterocycles.