Photoinduced rearrangement of diarylethenes to naphthalenes or isoelectronic benzoannulated heterocycles is a novel reaction in preparative organic photochemistry. Recently it was shown that unsymmetrical diarylethenes containing benzene and oxazole derivatives efficiently undergo this transformation leading to amide derivatives of naphthalene. Mechanistic study of skeletal rearrangement for a typical representative of these compounds, namely 3-(5-methyl-2-phenyl-1,3-oxazol-4-yl)-2-phenylcyclopent-2-en-1-one, was performed by stationary and laser flash photolysis as well as density functional theory (DFT) calculations. The mechanism of the rearrangement was found to comprise several thermal stages. Both singlet and triplet states of the initial compound can be transformed to the reaction product, which results in the dependence of the quantum yield vs concentration of dissolved oxygen. Three reactive intermediates were registered in the laser flash photolysis experiment; the predicted structures were in accordance with DFT calculations of the electronic absorption spectra. In addition to the previously proposed mechanism of skeletal rearrangement based on a sigmatropic shift of hydrogen, two new parallel pathways based on formation of a carbanion/carbocation were determined.

中文翻译：

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2,3-二芳基环戊烯酮带有苯和恶唑部分的光诱导重排的机理

二芳烃到萘或等电子苯并环杂环的光诱导重排是制备型有机光化学中的一种新型反应。最近显示，含有苯和恶唑衍生物的不对称二芳烃有效地经历了这种转化，从而生成了萘的酰胺衍生物。对这些化合物的典型代表，即3-（5-甲基-2-苯基-1,3-恶唑-4-基）-2-苯基环戊-2-en-1-one，进行了骨架重排的机理研究。通过固定和激光闪光光解以及密度泛函理论（DFT）计算。发现重排的机理包括几个热阶段。初始化合物的单重态和三重态都可以转化为反应产物，这导致了量子产率对溶解氧浓度的依赖性。在激光闪光光解实验中注册了三种反应中间体。预测的结构与电子吸收光谱的DFT计算一致。除了先前提出的基于氢的σ迁移的骨架重排机制之外，还确定了基于碳负离子/碳化的形成的两个新的平行途径。