Interest in sulfonium compounds has been stimulated by their useful application as raw materials for the synthesis of drugs and sulfur-containing natural compounds, 1 and a convenient source of carbon radicals via a one-electron reduction. 2 In addition, aryl sulfonium salts are highly photosensitive and can be utilized as efficient photochemical sources of strong Brønsted acids for cationic polymerization of olefins or epoxides and ...