Methoxy-Substituted Stilbenes, Styrenes, and 1-Arylpropenes: Photophysical Properties and Photoadditions of Alcohols
作者:Jeffrey C. Roberts、James A. Pincock
DOI:10.1021/jo052123d
日期:2006.2.1
nucleophile are attached to two adjacent atoms of the original alkene double bond. Irradiation of the corresponding methoxy-substituted styrenes and trans-1-arylpropenes in TFE produced the analogous solvent adducts. The photoaddition of TFE proceeded with the general order of reactivity: styrenes > trans-1-arylpropenes > trans-stilbenes. Transient carbocation intermediates were observed following laser
反式苯乙烯和四种甲氧基取代的苯乙烯衍生物的光化学已经在多种溶剂中进行了研究。所有的五个反式异构体的荧光都被2,2,2-三氟乙醇(TFE)淬灭。在TFE中照射五种底物后,检测到源自溶剂光加成的产物。通过在TFE-OD中辐射形成的产物的核磁共振波谱表明,质子和亲核试剂连接到原始烯烃双键的两个相邻原子上。在TFE中辐照相应的甲氧基取代的苯乙烯和反式-1-芳基丙烯产生了类似的溶剂加合物。TFE的光加成反应按一般反应顺序进行:苯乙烯>反式-1-芳基丙烯>反式-苯乙烯基苯。在1,1,1,3,3,3-六氟-2-丙醇(HFIP)中对苯乙烯进行激光快速光解后,观察到瞬态碳正离子中间体。该结果与一种机制有关,该机制涉及通过TFE或HFIP对底物进行光子化,然后对短寿命碳正离子中间体进行亲核捕获。与其他二苯乙烯衍生物相比,反式-3,5-二甲氧基二苯乙烯在极性有机溶剂中显示出大的荧光量子产率和低的反式顺式异构化量子产率。的独特光物理性质的反式-3