Aliphatic C-H Functionalization Using Pyridine N -Oxides as H-Atom Abstraction Agents.

The alkylation and heteroarylation of unactivated tertiary, secondary, and primary C(sp 3 )-H bonds was achieved by employing an acridinium photoredox catalyst along with readily available pyridine N oxides as hydrogen atom transfer (HAT) precursors under visible light. Oxygen-centered radicals, generated by single-electron oxidation of the N oxides, are the proposed key intermediates whose reactivity can be easily modified by structural adjustments. A broad range of aliphatic C-H substrates with electron-donating or -withdrawing groups as well as various olefinic radical acceptors and heteroarenes were well tolerated.