Recyclable copper catalyzed nitrogenation of biphenyl halides: a direct approach to carbazoles

A novel A21-CuI catalyzed direct nitrogenation of biphenyl halides for the direct synthesis of carbazoles via a direct C-H amination process has been developed. A recyclable and inexpensive Cu-catalyst was successfully employed in N-heterocyclic compound synthesis via tandem azidation and C-H amination, which makes this protocol very practical and easy to handle.