Palladium-Catalyzed Synthesis of Tricyclic Indoles via a N–S Bond Cleavage Strategy

In palladium/norbornene (Pd/NBE) chemistry, the “ortho effect” has been proven to be a key factor in the process of β-carbon elimination to extrude NBE. Herein, we found that the o-iodoaniline protected by a p-methoxybenzenesulfonyl group can recover the “ortho effect” and then undergo N–S bond cleavage with vinyl palladium, thus achieving a highly selective C–N coupling reaction in the Catallani–Lautens reaction system. On the basis of this discovery, a one-step synthesis of highly functionalized tricyclic indole derivatives was realized.