Photoredox Copper Catalysis for C3–H Nitroalkylation of Quinoxalinones via Nitroalkyl Radicals

We report a novel copper‐catalyzed photocatalytic method for the direct C3–H nitroalkylation of quinoxalin‐2(1 H )‐ones via selective generation of primary α‐nitroalkyl radicals from simple nitroalkanes. The transformation proceeds under mild conditions at room temperature, uses air as the terminal oxidant, and is without external photocatalyst. A broad range of substituted quinoxalin‐2(1 H )‐ones and unactivated aliphatic nitroalkanes undergo selective C3 functionalization in good to excellent yields, with exclusive C═H over N═H alkylation. Mechanistic studies, including radical trapping, UV–visible spectroscopy, EPR, and XPS analysis, support a copper‐mediated radical pathway involving ligand exchange, nitronate coordination, and photoinduced ligand‐to‐metal charge transfer (LMCT) to generate nitroalkyl radicals. Subsequent radical addition and copper‐assisted oxidative rearomatization furnish the products while regenerating the active Cu(II) catalyst. The method is operationally simple, scalable, and enables downstream functionalization of the nitro group, providing efficient access to value‐added quinoxalinone derivatives.