Photoisomerization of Sultams Derived from Saccharin; Part 3: Dihydro[1]benzothieno[3,2-b]pyrrole 4,4-Dioxides from Dihydropyrrolo[1,2-b][1,2]benzisothiazole 5,5-Dioxides

Abstract 1-Substituted 2,3-dihydropyrrolo[1,2-B][1,2]benzisothiazole 5,5-dioxides 7A-C,E undergo a smooth and efficient transformation into the 2,3-dihydro[1]benzothieno[3,2-B]pyrrole 4,4-dioxides 8A-C,E upon irradiation at 254 nm in acetonitrile. The structures of the products have been elucidated by spectroscopic methods and a single crystal X-ray structure determination for 8B.