Cu₂O/Cs₂CO₃/DMF: An efficient catalytic system for N-arylation of imidazole with aryl halides under ligand-free conditions

A ligand-free Cu-catalyzed protocol for the Ullmann-type N-arylation of N-containing heterocycles with aryl or heteroaryl iodides and bromides has been established. A broad range of functional groups is well tolerated on both of the cross-coupling partners, producing the desired products in good to excellent yields.