Visible‐Light‐Induced Radical Cascade Cyclizations of 1,7‐Enynes with Sulfinic Acids: Direct Access to Sulfonated Chromanes and Sulfonated Tetrahydroquinolines under Metal‐Free Conditions

Abstract Visible‐light‐induced strategy to access sulfonated chromanes and sulfonated 1,2,3,4‐tetrahydroquinolines via a radical cascade cyclization of 1‐(arylethynyl)‐2‐(vinyloxy)benzenes and N ‐allyl‐2‐(arylethynyl)anilines with aromatic and aliphatic sulfinic acids has been developed. In the presence of TBHP (7.5 mol%) as an oxidant and Eosin Y (3.0 mol%) as a photocatalyst, the reactions undergo smoothly to afford the corresponding products in good yields at room temperature under metal‐free conditions. This transformation features low loading of TBHP, mild reaction conditions, simple operation, broad functional‐group tolerance, and good yields of products. magnified image