Abstract We report herein that a commercially available CeO2 is an active and reusable catalyst for the C3-selective alkenylation of oxindole with aldehydes under solvent-free conditions. This catalytic method is generally applicable to different aromatic and aliphatic aldehydes, giving 3-alkyledene-oxindoles in high yields (87%–99%) and high stereoselectivities (79%–93% to E-isomers). This is the first example of the catalytic synthesis of 3-alkenyl-oxindoles from oxindole and various aliphatic aldehydes. The Lewis acid-base interaction between Lewis acid sites on CeO2 and benzaldehyde was studied by in situ IR. The structure-activity relationship study using CeO2 catalysts with different sizes suggests that defect-free CeO2 surface is the active site for this reaction.

中文翻译：

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使用非均相 CeO2 催化剂选择性 C3-烯基化羟吲哚与醛

摘要 我们在本文中报道，市售的 CeO2 是一种活性且可重复使用的催化剂，可用于在无溶剂条件下将 oxindole 与醛进行 C3 选择性烯基化。这种催化方法通常适用于不同的芳香族和脂肪族醛，以高产率（87%–99%）和高立体选择性（79%–93% 的 E-异构体）得到 3-亚烷基-羟吲哚。这是从羟吲哚和各种脂肪醛催化合成 3-烯基-羟吲哚的第一个例子。通过原位 IR 研究了 CeO2 上的路易斯酸位点与苯甲醛之间的路易斯酸碱相互作用。使用不同尺寸的 CeO2 催化剂的构效关系研究表明，无缺陷的 CeO2 表面是该反应的活性位点。