Irradiation of indole or isocarbostyril derivatives with allenyl side chain under appropriate conditions gave the corresponding methylenecyclobutane-fused N-heterocycles stereoselectively in high yields through intramolecular [2+2] cycloaddition. These addition products could be transformed to ring-expanded compounds without loss of the configuration by using a sequence of epoxidation and skeletal rearrangement.

中文翻译：

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亚甲基环丁烷稠合 N-杂环衍生的环氧化物的立体定向骨架重排

在适当的条件下，对具有联烯基侧链的吲哚或异喹诺酮衍生物进行照射，通过分子内[2+2]环加成，以高产率立体选择性地得到相应的亚甲基环丁烷稠合的N-杂环。通过使用一系列环氧化和骨架重排，这些加成产物可以转化为扩环化合物，而不损失构型。