The 193-nm Photochemistry of Some Fused-Ring Cyclobutenes: Absence of Orbital Symmetry Control

Article abstract of DOI:10.1021/jo00238a023

The photochemistry of cis-bicyclo<6.2.0>dec-9-ene (1), cis-bicyclo<6.2.0>deca-2,9-diene (4), and trans-bicyclo<6.2.0>deca-2,9-diene (8) has been examined at 193 nm in pentane solution.The photochemistry of 1 was complicated by the apparent formation of the thermally labile diene 15, which prevented direct determination of the primary photoproducts of 1.Dienes 4 and 8 were found to eliminate acetylene stereoselectively to give mainly the syn-elimination products 17 and 18, respectively.Ring opening of 4 and 8 gave, as primary products, trienes 5, 6, and 16, indicating that the stereospecificity suggested by the Woodward-Hoffmann rules of orbital symmetry was not followed.