Semin D J, Winkler P C, Rowlen K L
University of Colorado, Department of Chemistry and Biochemistry, Boulder 80309.
Photochem Photobiol. 1994 Sep;60(3):185-95. doi: 10.1111/j.1751-1097.1994.tb05089.x.
Methyl-substituted psoralens (4'-(hydroxymethyl)-4,5',8-trimethylpsoralen and 4,5',8-trimethylpsoralen) are found to yield an ene product as well as the expected [2 + 2] cycloaddition product from photochemical reaction with simple olefins. As determined by absorbance, liquid chromatography-mass spectrometry and nuclear magnetic resonance, both products are formed at the pyrone side of the respective psoralen. The product distribution is dependent on olefin concentration as well as the nature of the olefin. In deoxygenated solutions, cyclic olefins form as much as 50% ene product, while unsubstituted straight-chain olefins form as little as 3%. In oxygenated solutions, the product distribution is strongly affected by singlet oxygen.
甲基取代的补骨脂素（4'-(羟甲基)-4,5',8-三甲基补骨脂素和4,5',8-三甲基补骨脂素）被发现与简单烯烃发生光化学反应时，除了生成预期的[2 + 2]环加成产物外，还会生成一个烯反应产物。通过吸光度、液相色谱-质谱联用和核磁共振测定，两种产物均在各自补骨脂素的吡喃酮侧形成。产物分布取决于烯烃浓度以及烯烃的性质。在脱氧溶液中，环状烯烃形成的烯反应产物高达50%，而未取代的直链烯烃形成的烯反应产物低至3%。在含氧溶液中，产物分布受到单线态氧的强烈影响。
