Framework-Copper-Catalyzed C-N Cross-Coupling of Arylboronic Acids with Imidazole: Convenient and Ligand-Free Synthesis of N-Arylimidazoles

A convenient and environmentally benign synthesis of N-arylimidazoles has been demonstrated by a straightforward reaction catalyzed by the unsaturated coordination sites of Cu in the copper terephthalate metal-organic framework (Cu(tpa)-MOF). A series of N-arylimidazoles has been synthesized in excellent yields by the C-N cross-coupling reaction of arylboronic acids and imidazoles catalyzed by the Cu(tpa)-MOF using ethanol as a benign solvent. The present ligand-free catalytic system proceeds smoothly under mild conditions, avoids stoichiometric Cu reagents, tolerates many functional groups, has a wide substrate scope, and is feasible with other nitrogen heterocycles. The stability and heterogeneity of the catalyst is evidenced by the results of a heterogeneity test, and the catalyst can be reused several times without a loss of activity. The easy preparation of the catalyst, its stability, recovery by simple filtration, and reusability reveal Cu(tpa) MOF as a versatile catalyst for academic and industrial applications.