Pd^II-Catalyzed Di‑<i>o</i>‑olefination of Carbazoles Directed by the Protecting <i>N</i>‑(2-Pyridyl)sulfonyl Group

Abstract

Despite the significance of carbazole in pharmacy and material science, examples of the direct C–H functionalization of this privileged unit are quite rare. The <i>N</i>-(2-pyridyl)sulfonyl group enables the Pd^II-catalyzed <i>ortho</i>-olefination of carbazoles and related systems, acting as both a directing and readily removable protecting group. This method features ample structural versatility, affording typically the double <i>ortho</i>-olefination products (at C1 and C8) in satisfactory yields and complete regiocontrol. The application of this procedure to related heterocyclic systems, such as indoline, is also described