Palladium-Catalyzed Cyclization of <i>N</i> -(2-Iodoaryl)- <i>N</i> -methylbenzenesulfonamide with Aryl Iodides to Access Phenanthridine Derivatives

This work presents a method for the synthesis of phenanthridine derivatives based on the activation of <i>N</i>-methyl sp³ C-H bonds. A systematic investigation was conducted on the palladium-catalyzed cross-coupling reaction between <i>N</i>-(2-iodoaryl)-<i>N</i>,2,4,6-tetramethylbenzenesulfonamide and aryl iodides, achieving selective control over both double and triple coupling pathways to access phenanthridine and 4-arylated phenanthridine derivatives. Furthermore, the alkaloid trisphaeridine was successfully synthesized, offering a concise and practical new strategy for the preparation of phenanthridine-based alkaloids and pharmaceutical agents.