Synthesis of β ‐Carbolines via a Photoredox‐Catalyzed Cascade Cyclization and Aromatization of Tryptophan Derivatives

A mild and efficient method for the synthesis of β ‐carbolines has been developed, based on a visible‐light‐induced cascade cyclization and aromatization of tryptophan derivatives, enabling the key C‐ring formation within the tricyclic core structure. Instead of traditional acid‐promoted conditions, a neutral photoredox catalyst is employed, and the reaction is carried out under mild, acid‐ and base‐free conditions. A variety of β ‐carboline frameworks can be efficiently accessed through this streamlined one‐pot strategy employing a ruthenium‐based photocatalyst.