Regioselective Pd-catalyzed indolization of 2-bromoanilines with internal alkynes using phosphine-free ligands

The possibility of using phosphine-free ligands to promote Pd-catalyzed indolization of 2-bromoanilines with internal alkynes was examined for the first time. Phenylurea was found to be the optimal ligand, which could mediate the synthesis of 2,3-disubstituted indoles in good yields (ca. 60–85%) with high regioselectivity.