Direct α-C(sp³)─H Alkylation and Arylation of Ethers Enabled by Carbon Nitride/Nickel Metallaphotoredox Catalysis

The direct functionalization of α-C(sp³)─H bonds offers a powerful strategy for converting abundant feedstocks and complex molecules into value-added products, yet sustainable catalytic platforms that avoid precious-metal photocatalysts remain underdeveloped. Here, we report a metallaphotoredox system that combines recyclable carbon nitride nanosheets with nickel catalysis for the direct α-C(sp³)─H cross-coupling of ethers, amides, and benzylic substrates under visible light. The method operates at mild temperature in air and enables both α-C(sp³)─C(sp²) and α-C(sp³)─C(sp³) bond formation using aryl and alkyl halides, including challenging ether donors such as THF, 2-MeTHF, 1,4-dioxane, and DME. Broad functional group tolerance is demonstrated across electronically diverse aryl halides, while late-stage alkylation of pharmaceutically relevant molecules including loratadine, caffeine, and fenofibrate highlights the utility of the platform for molecular diversification. The carbon nitride photocatalyst is readily recovered and reused over five cycles without loss of activity, and the process is further translated to continuous flow, providing accelerated reaction kinetics and reduced photocatalyst loading. Mechanistic studies combining Stern-Volmer analysis, radical trapping, cyclic voltammetry, NMR spectroscopy, and DFT calculations support a dual catalytic cycle in which photoexcited carbon nitride promotes oxidative generation of α-heteroatom-stabilized radicals, while nickel mediates radical capture, cross-coupling, and product-forming reductive elimination. This work establishes carbon nitride as an earth-abundant, recyclable alternative to noble-metal photocatalysts for metallaphotoredox C─H functionalization and expands the scope of heterogeneous photocatalysis to direct α-C(sp³)─H cross-coupling.