Facile synthesis of 2-bromoindoles by ligand-free CuI-catalyzed intramolecular cross-coupling of gem-dibromoolefins

A mild and efficient synthesis of 2-bromoindoles by ligand-free CuI-catalyzed intramolecular cross-coupling of gem-dibromoolefins was developed. Reactions were carried out in toluene at room temperature and the corresponding 2-bromoindoles were obtained in excellent yields.