Pd(II)/Bu₄NBr/DMSO catalytic system for practical synthesis of indoles and pyrroles from imines through aerobic dehydrogenative cyclization

N-Aryl- and N-allylimines derived typically from substituted acetophenones undergo palladium(II)-catalyzed dehydrogenative cyclization reactions in the presence of tetrabutylammonium bromide and molecular oxygen in DMSO to afford indole and pyrrole derivatives, respectively, in moderate to good yields. The reactions are operationally simple and can be readily performed on multigram scales (up to 55 mmol).