Photoisomerization of Sultams Derived from Saccharin; Part 3: [1] [2] 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.

Key words

photoisomerization - sultams - dihydro[1]benzothieno-[3,2-b]pyrrole 4,4-dioxides

References

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10

Crystal data and structure refinement: Crystal size 0.55 × 0.24 × 0.18 mm, from MeOH. C₁₂H₁₁NO₄S, formula weight 265.28. Triclinic system, P-1. Unit cell dimensions: a = 6.923(2), b = 7.126(2), c = 12.471(3) Å; α = 82.67(2), β = 78.60(2), γ = 73.52(2)°; Z = 4, cell volume 576.6(3) ų, d_C = 1.528 g cm^-3, λ = 0.71073 Å (MoK_α ), µ = 0.287 mm^-1. F(000) = 276, Θ = 2.99-27.00°, limiting indices -8 ≤ h ≥ 0,
-9 ≤ k ≥ 8, -15 ≤ l ≥ 15. A Siemens P4RA four-circle diffractometer with graphite monochromator and scintillation counter was used to collect 2728 reflections, 2514 of which were unique (R _int = 0.0204). Ψ-Scan, transmission range 0.884-0.794. Refinement method: Full-matrix least-squares on F², 2514 data, 165 parameters. Goodness of fit on F² 1.082, final R indices, all data ( I ≥ 2σ(I)), R1 = 0.0361 (0.0323), wR2 = 0.0885 (0.0855). Extinction coefficient: 0.013(3). Residual electron density between -0.367 and 0.445 eÅ^-3. The programs SHELXS-97 for crystal structure solution and SHELXL-97 for crystal structure refinement by Sheldrick, G. M., University of Göttingen, Germany, 1997 have been used. All crystallographic data have been deposited at the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-152473. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK.