Photoinduced Copper‐Catalyzed Cross‐Coupling of Acylsilanes with Heteroarenes via Bimetallic Relay

Abstract The transition metal‐catalyzed direct coupling reactions involving electron‐rich Fischer carbene species are largely underdeveloped and remain a big challenge. Here, a direct coupling reaction of azoles and azine N ‐oxides is reported with Fischer copper carbene species bearing an α ‐siloxy group i, which can be in situ generated from acylsilanes catalytically under photoirradiation and redox‐neutral conditions. This coupling reaction between electron‐rich α ‐siloxy Fischer Cu‐carbene species with hard carbanion nucleophiles may undergo a bimetallic relay process, which is confirmed by the kinetic analysis and in situ NMR analysis. This reaction features mild conditions and remarkable heterocycle compatibility. Notably, this protocol tolerates a series of azole or azine N ‐oxide derivatives, including benzoxazole, benzothiazole, benzoimidazole, benzoisoxazole, oxazole, oxadiazole, triazolo[4,3 ‐a ]pyridine, purine, caffeine, pyridine N ‐oxide, quinoline N ‐oxide, pyrazine N ‐oxide, pyridazine N ‐oxide, etc. The synthetic value of this approach is demonstrated by the efficient synthesis of a histamine h4 receptor ligand and a marketed drug carbinoxamine.