A novel N-heterocyclic carbene-catalyzed asymmetric [4 + 2] annulation of in situ generated oxindole-embedded o-quinone methides with aldehydes has been developed for synthesis of complicated spirooxindoles. The methodology provides facile, straightforward access to various enantioenriched spirooxindole lactones bearing a chiral quaternary carbon center in high yield (up to 98%) with diastereoselectivity (up to >20 : 1 dr) and excellent enantioselectivity (up to >99% ee).

中文翻译：

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NHC 催化原位生成的羟吲哚嵌入邻醌甲基化物和醛立体选择性合成螺吲哚内酯

一种新型的N-杂环卡宾催化的原位生成的羟吲哚嵌入邻醌甲基化物与醛的不对称[4 + 2]成环反应已被开发用于合成复杂的螺吲哚。该方法能够以高产率（高达 98%）、非对映选择性（高达 >20 : 1 dr）和优异的对映选择性（高达 >99% ee）轻松、直接地获得各种带有手性季碳中心的对映体富集的螺吲哚内酯。