Copper-catalyzed synthesis of five-membered heterocycles via double C-N bond formation: an efficient synthesis of pyrroles, dihydropyrroles, and carbazoles

An efficient copper-catalyzed double C-N bond forming reaction using diiodides and nitrogen-centered nucleophiles including amides and carbamates is reported. The reactions proceed to afford di- or tri-substituted N-acylpyrroles, dihydropyrroles, and carbazoles in good to excellent yields when different diiodides such as 1,4-diiodo-1,3-butadienes, 1,4-dihalobut-1-enes, and 2,2′-diiodobiphenyls were employed, respectively. It is crucial to use CuI as the catalyst with the assistance of proper base and diamine ligand.