Readily available and facilely tunable pyridine N-oxides have been developed as effective photoinduced hydrogen-atom-transfer (HAT) catalysts for site-selective C–H functionalizations of a broad range of C–H substrates, including unactivated alkanes. Pyridine N-oxide radicals, catalytically generated from N-oxides by photoredox catalyzed single-electron oxidation, are the key intermediates that enable an effective HAT process for carbon radical generation to achieve alkylation, amination, azidation, allylation, and cyanation. Additionally, the fine-tuning of reactivity and selectivity of pyridine N-oxides through operationally simple structural modification was investigated and showed promising capability for selective functionalization of unactivated C­(sp3)–H bonds.

Readily available and facilely tunable pyridine N-oxides have been developed as effective photoinduced hydrogen-atom-transfer (HAT) catalyst for site-selective C-H functionalizations of a broad range of C-H substrates, including unactivated al-kanes. Pyridine N-oxide radicals, catalytically generated from N-oxides by photoredox catalyzed single-electron oxidation, are the key intermediate that enable effective HAT process for carbon radical generation to achieve alkylation, amination, azidation, and allylation. Additionally, the fine tuning of reactivity and selectivity of pyridine N-oxides through operationally simple structural modification was investigated and shown promising capability for selective functionalization of unactivat-ed secondary and primary C(sp3)–H bonds.