Ring-Cleavage Reactions of Small-Ring Compounds by Photo- Induced Electron Transfer

（1）由芳香硝酸盐引起的2，2-二氧化物的光敏环清除反应。通过电子接受器对2，2-二氧化物的光敏反应，将这样的环清除产品作为替代苯并酮和烯烃，已被调查。量子年用于环清除不同的化合物，同时含有芳基组和氧化物环。量子场因氧化物的电子捐助能力而增加，而增加了量子场。在1，4-二甲基萘-光敏感反应的情况下，在2，2-di-p-tolyl-或2，2-bis（p-methoxyphenyl）-3，3，4-三甲基溴酮exceed unit中的有限量子年。（2）2，2-二氧烷在电子捐赠者中的光化学反应。光化学环-清除反应在三乙胺的存在中，有选择地给予1，1-二苯胺。（3）1、2-环环球环的环清除反应。我们发现了一个aryl替代的环球，揭示了在光化学和热环分裂反应中的可显著结构依赖性。“reactive”和“unreactive”cyclobutances。因此，通过单晶体X射线分析法确定的二酰环球素的分子结构。Although the distances and angles of cyclobutane rings are relatively normal， the torsional angles between the plane involving the ipso carbon and the aryl-substituted carbons of cyclobutane ring are close to 90 in the cases of“reactive”cyclobutane ring but vary small in the cases of“unreactive”cyclobutes。

(1) photosensitized Ring-Cleavage Reaction of 2,2-Diaryloxetanes by Aromatic Nitriles. Photosensitized reactions of 2,2-diaryloxetanes by electron acceptors, which give such ring-cleavage products as substituted benzophenones and alkenes, have been investigated. Quantum yields for the ring cleavage vary with substituents on both the aryl group and oxetane ring. The quantum yield increases with increase in electron-donating ability of the oxetane. The limiting quantum yields in the case of 1,4-dicyanonaphthalene-photosensitized reaction of 2,2-di-p-tolyl- or 2,2-bis(p-methoxyphenyl)-3,3,4-trimethyloxetane exceed unity.(2) Photochemical Reactions of 2,2-Diaryloxetanes in the Presence of Electron Donor. Photochemical ring-cleavage reactions of 2,2-diaryloxetanes in the presence of triethyl-amine occurred to give 1,1-diarylethene selectively.(3) Ring-Cleavage Reactions of 1,2-Diarylcyclobutanes. We found that aryl-substituted cyclobutanes reveal remarkable structure dependences in photochemical and thermal ring-splitting reactions. The reactivities of cyclobutanes are explic-itly classified into two groups of "reactive" and "unreactive" cyclobutances. Therefore, molecular structures of diarylcyclobutanes have been determined by single-crystal X-ray analyses. Although the distances and angles of cyclobutane rings are relatively normal, the torsional angles between the aryl ring and the plane involving the ipso carbon and the aryl-substituted carbons of cyclobutane ring are close to 90゜ in the cases of "reactive" cyclobutanes but vary small in the cases of "unreactive" cyclobutanes.