Pd-Catalyzed Triple-Fold C(sp2)-H Activation with Enaminones and Alkenes for Pyrrole Synthesis via Hydrogen Evolution.

The synthesis of NH-free pyrroles via Pd-catalyzed annulation of enaminones and alkenes is reported. With the catalysis of Pd(II), the activation of triple C(sp2)-H bonds, including one internal C(sp2)-H bond in enaminone, has been activated to provide various pyrroles. The interesting evolution of hydrogen gas from the reactions has been observed by a hydrogen detector.