Synthesis of Cyclic Sulfides through Tandem Nucleophilic Substitution and Photoredox-Mediated Intramolecular Thiosulfonylation

This study presents an efficient method for synthesizing cyclic sulfides through a tandem nucleophilic substitution and a photoredox-mediated intramolecular thiosulfonylation approach. Utilizing readily available bromoalkane-tethered alkynes and potassium thiosulfonate salts, the protocol enables the construction of five-, six-, and seven-membered sulfur-containing heterocycles under mild conditions. This one-pot strategy offers a broad substrate scope, good functional group tolerance, and high yields, avoiding harsh reagents or multistep procedures. Mechanistic studies support a radical-based cyclization mechanism.