As a model for light energy conversion, some fluoroalkylnorbornadienes were prepared using the Diels-Alder reaction between fluoroalkylpropiolates and cyclopentadienes having electron donating substituents (H-, Me-, C6H5-). Trifluoromethylpropiolate (5) shows the highest reactivity as a dienophile. Esters were converted to ketones which show an intramolecular charge transfer absorption. Irradiation
作为光能转化的模型,使用
氟代烷基
丙酸酯和具有给电子取代基(H-,Me-,C 6 H 5-)的
环戊二烯之间的狄尔斯-阿尔德反应制备了一些
氟代烷基降
冰片二烯。
丙二酸三
氟甲基酯(5)作为亲二烯体显示出最高的反应活性。酯转化为显示分子内电荷转移吸收的酮。用高压
汞灯辐照具有酮基的三
氟甲基降
冰片二烯,定量得到相应的
四环烷。后来的化合物在室温下在苯中非常不稳定,逐渐还原为原始的降
冰片二烯。