Site-Selective Pyridine Carbamoylation Enabled by Consecutive Photoinduced Electron Transfer

The development of innovative approaches for synthesizing amide motifs is consistently in high demand. Herein, we successfully employ readily available oxamic acids as carbamoyl radical precursors to couple with pyridinium salts under metal-free conditions, selectively introducing the amide group into pyridine architectures. The key innovation lies in the successful integration of an acridinium-based photocatalyst, which enables the formation of amide bonds through a consecutive photoinduced electron transfer process. This open-shell strategy exhibits remarkable tolerance toward a wide range of functional groups. Furthermore, the applicability of this method has been extended to complex motifs, demonstrating its versatility. Importantly, this approach serves as a complementary strategy to classical amidation synthesis, offering potential advantages such as improved selectivity and expanded synthetic possibilities.