Air-Tolerant Copper Catalysis for C–N Cross-Coupling Reactions: Catalyst Reactivation Enabled by Silane Additives

The applicability of many transition-metal-catalyzed reactions is limited by sensitivity to air and moisture. Copper-catalyzed aromatic carbon–nitrogen bond formation is a versatile and economical synthetic tool, yet most catalytic systems require an inert atmosphere to prevent catalyst deactivation. Rather than developing new catalysts for individual transformations, we now report a silane-enabled catalyst-reactivation strategy that maintains active Cu(I) species under aerobic conditions by reducing off-cycle Cu(II) species. The protocol obviates the use of a glovebox, Schlenk techniques, or degassed solvents, while enabling a wide variety of copper-catalyzed C–N bond-forming processes—including amination, amidation, sulfonamidation, and N-heterocycle arylation—to proceed efficiently under air without compromising good functional group tolerance and chemoselectivity. This strategy provides a general solution to mitigate catalyst deactivation, substantially enhancing the practicality of copper catalysis.