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

Article abstract of DOI:10.1002/adsc.202000846

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. (Figure presented.).