For the first time, visible-light as a benign, green, and an inexpensive source has been successfully employed to the synthesis of 3-indolyl-3-hydroxy oxindoles in extremely mild reaction conditions in the absence of any catalyst. Using this sustainable photoinduced approach, various isatins and indoles containing electron-withdrawing groups and electron-donating groups gave the corresponding products in moderate to good yield in water at room temperature. The formation of a CT complex between indoles and isatins is significant to proceed this photochemical reaction.

中文翻译：

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可见光介导的无催化剂的水中3-吲哚基-3-羟基羟吲哚的合成

首次将可见光作为一种良性，绿色和廉价的光源成功地用于在没有任何催化剂的情况下，在极其温和的反应条件下合成3-吲哚基-3-羟基羟吲哚。使用这种可持续的光诱导方法，在室温下，含有吸电子基团和给电子基团的各种靛红和吲哚类化合物在水中以中等至良好的收率得到了相应的产物。吲哚和靛红之间CT复合物的形成对于进行这种光化学反应很重要。