Here we report a carbene-catalyzed enantio- and diastereoselective [4+2] cycloaddition reaction of cyclobutenones with isatins for the quick and efficient synthesis of spirocyclic δ-lactones bearing a chiral chlorine. A broad range of substrates with various substitution patterns proceed smoothly in this reaction, with the spirooxindole δ-lactone products afforded in generally good to excellent yields and optical purities under mild reaction conditions.

中文翻译：

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卡宾催化[4+2]环丁烯酮和靛红的环加成反应快速生成手性含氯螺环δ-内酯

在这里，我们报道了卡宾催化的环丁烯酮与靛红的对映和非对映选择性[4+2]环加成反应，用于快速有效地合成带有手性氯的螺环δ-内酯。具有各种取代模式的多种底物在此反应中顺利进行，在温和的反应条件下，螺吲哚δ-内酯产物通常具有良好至优异的产率和光学纯度。