Catalytic Aldehyde–Alkyne Couplings Triggered by Ketyl Radicals

A general and flexible platform for catalytic aldehyde-alkyne couplings triggered by ketyl radicals is described. This open-shell strategy necessitates only a catalytic quantity of a photoredox catalyst, along with Hünig's base (DIPEA) as a halogen atom transfer reagent. The reaction proceeds through sequential steps involving activation, halogen atom transfer, and radical addition. This carbonyl-alkyne coupling exhibits a wide substrate scope and functional group compatibility and has been successfully applied to the late-stage modification of complex architectures.