Copper-Mediated Oxidative Radical Addition/Cyclization Cascade: Synthesis of Trifluoromethylated and Sulfonated Quinoline-2,4(1H,3H)-diones

A copper-mediated oxidative radical addition/cyclization cascade of o-cyanoarylacrylamides with sodium trifluoromethanesulfonate (Langlois' reagent) has been achieved. The reaction proceeds through radical addition, cyclization, and imine hydrolysis, in which the cyclization was accomplished by an intramolecular addition of the carbon radical to the nitrile. This transformation exhibits a wide substrate scope and good functional group tolerance, thus providing a highly efficient and practical access to a variety of trifluoromethylated quinoline-2,4(1H,3H)-diones. Furthermore, using other sulfinic acid sodium salts as sulfonylating agents, sulfonated quinolinediones were also obtained through a similar radical cascade.