Highly Efficient N, O Donor Ligand‐Assisted Copper Complex‐Catalyzed N‐Arylation of Nitrogen‐Containing Heterocycles with Aryl Halides

Herein, we have successfully implemented two dinuclear copper complexes based on N, O donor ligands as efficient and selective catalysts for the arylation of N‐heterocycles using aryl iodides, aryl bromides, and even less reactive aryl chlorides under relatively mild conditions. This is a dinuclear approach where metal–metal cooperation through a bridging ligand can enhance the catalytic process more efficiently than traditional mononuclear complexes. The structural characterization of a dinuclear copper complex of the form Cu 2 L 1 4 , 1 based on N, O donor 8‐hydroxyquinoline (HL 1 ), reveals the formation of interesting isomeric structures. The complex 1 shows better catalytic activity toward N‐arylation compared to the bis‐chelating Schiff base N, O donor 2,2 ′ ‐naphthalene‐1,5‐diylbis(nitrilo­methanylyl­idene)diphenol (H 2 L 2 )‐coordinated dinuclear copper complex ClCu(μ‐L 2 )CuCl, 2 . The current protocol is effective for the arylation of imidazole, pyrazole, benzimidazole, 1,2,4‐triazole, pyrrole, and indole, with tolerance of common functional groups. The N‐arylation reaction catalyzed by 1 has been successfully scaled up to Gram scale without significantly reducing the product yield. A mechanistic route for this N‐arylation reaction has been proposed by considering various control experimental and spectroscopic results.