Regioselective cascade annulation of indoles with alkynediones for construction of functionalized tetrahydrocarbazoles triggered by Cp*RhIII-catalyzed C–H activation

Abstract

An efficient regioselective and stereoselective cascade annulation of indoles with alkynediones has been demonstrated via a Cp*Rh^III-catalyzed indole C2–H activation by using N-carboamide directing groups in good to excellent yields with a broad substrate scope, which further realized the C2 and C3 difunctionalization of indoles in one-pot. This methodology simultaneously provides a novel and straightforward approach to free (NH) tetrahydrocarbazoles with continuous quaternary carbons and pyridoindolones, which are valuable intermediates in total synthesis of the related indole alkaloids.