联苯基团引起的激发三重态重排活性增长

Enhanced Triplet Reactivity of Photorearrangement by Biphenylyl Moiety

双发色团分子光化学研究兴趣与日俱增。我们在以前报道一个有趣的现象:基态发色团间的分子轨道交叠左右光反应机理。3-甲基-3-联苯基-1-丁烯(1),是有特殊意义的分子。与激发能高达(143 kcal/mol)的孤立双键相比,联苯基的激发能特别低(69 kcal/mool)。如此大的激发能差使乙烯基与联苯 p电子间的交叠通道更加畅通,基态1的稳定构象是 endo 型,1的光化学行为将不同于无环双π甲烷分子。1000 W 高压汞灯照射1的正已烷溶液,

It has been established that the preferred and sterically more congested endo confi-guration of biphenylyl dimethyl vinyl methane alters the reaction mechanism and gives riseto enhanced reactivity of the triplet.The photorearrangement proceeds unconcertedly.