The photoreaction behaviors of 2,3-bis[2-(4-chlorophenyl)ethenyl]pyrazine (1) in the crystalline state as well as in acetonitrile solution were examined mechanistically. In the crystalline state, stepwise [2+2] cycloadditions occurred between two facing molecules under the crystal lattice control to give a [2.2]orthocyclophane derivative in 74% yield. Photoirradiations of 1 in acetonitrile solution were also performed. In this case, products distributions were changed depending on the cut off wavelength.
The photoreaction of 2,3-di[(E)-styryl]pyrazine derivatives was carried out in the crystallinestate and in solution. Among them, 2,3-di(p-chlorostyryl)pyrazine and 2,3-di(p-cyanostyryl)pyrazine were photoreactive in the crystallinestate and gave, upon photoirradiation, [2.2]orthocyclophanes in 76 and 58% yields, respectively. Such a topochemical photo-behavior was interpreted on the basis of X-ray
2,3-二[(E)-苯乙烯基]吡嗪衍生物的光反应在结晶状态和溶液中进行。其中,2,3-二(对-氯苯乙烯基)吡嗪和2,3-二(对-氰基苯乙烯基)吡嗪在结晶状态下具有光反应性,在光照射下分别以76%和58%的产率得到[2.2]正环芳烃. 在晶体的 X 射线晶体学分析的基础上解释了这种拓扑化学光行为。溶液中2,3-二苯乙烯基吡嗪的光辐照得到[2.2]正环芳烷和抗头尾型单环二聚体作为主要产物。产物的产率因溶剂而异;随着溶剂极性的降低,环烷的产率降低,而单环二聚体的产率增加。以类似的方式,其他 2 的光照射,