Arenethiolate-Catalyzed 1,5-HAT of Aryl Halides: Synthesis of γ-Spirolactams.

γ-Spirolactam is a privileged building block that is found in a wide range of natural products and bioactive compounds. Herein, we report an arenethiolate-catalyzed 1,5-HAT of aryl halides to obtain γ-spirolactams through a SET reduction/intramolecular 1,5-HAT/cyclization/HAT process. This protocol features metal-free conditions and a broad substrate scope, furnishing the γ-spirolactams in moderate to excellent yields. Notably, aryl bromides, aryl chlorides and even aryl fluorides are well tolerated in this transformation. A mechanism involving arenethiolate as a SET catalyst is proposed based on DFT calculation.