Oxidative Cyclization of Unsaturated Ketene Dithioacetals with Ceric Ammonium Nitrate to Form Bicyclic Lactones

Ceric ammonium nitrate oxidizes unsaturated ketene dithioacetals in wet MeCN to give cation radicals that cyclize to trisubstituted double bonds and styrenes by cation-like cyclizations leading to cyclic cation radicals that are transformed by further oxidation, hydrolysis and cyclization to bicyclic lactones in moderate to good yield.