Photoinduced C-H Acylation of Azauracil Derivatives with Aldehydes

A metal- and photosensitizer-free photoinduced C-H acylation of azauracils with both aryl and alkyl aldehydes has been developed using H2O2 or TBHP as the sole additive under light-emitting diode irradiation. This protocol accommodates a broad range of substrates, including various N-substituted azauracil derivatives as well as aryl, heteroaryl, and alkyl aldehydes, affording the corresponding acylated products in moderate to good yields. Notably, this transformation proceeds efficiently without transition metals or external photocatalysts, representing a distinct advantage over conventional protocols. The synthetic utility of this method is further demonstrated by scalable continuous-flow synthesis, late-stage functionalization of bioactive molecules, and diverse product derivatizations. Mechanistic studies, including radical trapping experiments and high-resolution mass spectrometry analysis of the corresponding adducts, support a radical pathway involving acyl radical intermediates and sequential hydrogen atom transfer processes.