Photoreactions of 3-tosyl- and 6-tosyldihydro-1,3-diazaazulanones to form 1,3-diazaazulanones and ionic pairs between p-toluenesulfonate anion and 1,3-diazadihydroazulanone cations

A solvent effect was found on the photoreactions of 1-aryl-3-tosyldihydro-1,3-diazaazulanones with a low pressure mercury lamp. Thus, ion pairs between p-toluenesulfonate anion and the corresponding 1-aryl-1,3-diazadihydroazulanone cations were afforded by the reactions in THF. On the other hand, the corresponding 1-aryl-1,3-diazaazulanones were formed by the reactions in the other solvents. The analogous photoreactions with 1-aryl-6-tosyldihydro-1,3-diazaazulanones afforded the corresponding 1-aryl-1,3-diazaazulanones.