A New Asymmetric Photoisomerization of 2,3-Dihydropyrrolo[1,2-b]benzisothiazole 5,5-Dioxides

A tricyclic ring system bearing new stereogenic center namely 2,3-dihydro[1]benzothieno[3,2-b]pyrrole 4,4-dioxide was synthesized by asymmetric photoisomerization of 2,3-dihydropyrrolo[1,2-b]benzisothiazole 5,5-dioxide by irradiation with 245 nm emission of the low-pressure mercury lamp. The chemical structure and the purity of the photoproduct were delineated preliminarily by IR, NMR, and MS and finally confirmed by single crystal X-ray crystallography.