Abstract 1, 2, 4, 5-Tetrasubstituted cyclopentadienes VIa-VIf or phenanthrene derivative VIII, respectively, were obtained as the main photoproducts upon irradiation of sulfones Ia-If and II in acetonitrile, methanol or benzene. Bridged isomers Va-Vd were isolated from the reaction of Ia-Id carried out in acetonitrile. Probable course of the investigated photochemical transformations of 4H-thiopyran-1, 1-dioxides is discussed.