Palladium-Catalyzed [2 + 2 + 2] Annulation via Transformations of Multiple C–H Bonds: One-Pot Synthesis of Diverse Indolo[3,2‑<i>a</i>]carbazoles

A Pd-catalyzed novel cascade reaction has been developed for the synthesis of indolo­[3,2a]­carbazoles involving multiple C–H transformation–annulations between the indoles and alkynes. The method involves molecular oxygen as the sole oxidant and is an effective and step-economic process