NOVEL PHOTOREACTIONS OF BENZHYDRYLIDENEQUADRICYCLANE AND QUADRICYCLANONE - A NEW ROUTE TO TRIMETHYLENEMETHANE AND OXYALLYL DERIVATIVES

The irradiation of 3-benzhydrylidenequadricyclane (1) generated a trimethylenemethane (TMM) derivative, 3-benzhydrylidenebicyclo[3.2.0]hept-6-ene-2,4-diyl (3), which dimerized and could be chemically captured by molecular oxygen and acrylonitrile, but not by furan, methanol, or ethyl vinyl ether. The triplet nature of 3 was confirmed by EPR, emission, and absorption spectra. By contrast, the irradiation of quadricyclanone (2) generated the singlet oxyallyl (OA), 3-oxobicyclo[3.2.0]hept-6-ene-2,4-diyl (4) which could be captured by furan, methanol, and ethyl vinyl ether, but not by molecular oxygen or acrylonitrile, indicating the zwitterionic and electron-accepting nature of 4.