Nitrile‐stabilized quaternary ammonium ylide as an effective aryl‐cyanomethylene transfer agent has been explored for the first time, which enables a spirocyclopropanation process with conjugated carboxamide of indole heterocycle. The developed In(OTf)3‐catalyzed method provides a straightforward, diastereoselective access to pharmaceutically relevant spiro‐cyclopropane‐2‐oxindole skeleton assembled with an α‐cyano and two (hetero)aromatic substitutions. The common difficulties of a cyclopropanation process, e.g., a conjugated carboxamide as valid substrate, cleavage‐susceptibility of amide bond, substrates scope limited to preferentially electron‐withdrawing group containing molecules, and the competing dehydrocyanation reaction of product generated from nitrile‐stabilized ylide have been overcome in the present spirocyclopropanation process.

中文翻译：

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腈稳定季铵叶立德作为芳基氰亚甲基转移剂：螺环氰基环丙基-2-羟吲哚的非对映选择性合成


首次探索了腈稳定的季铵叶立德作为有效的芳基氰亚甲基转移剂，它能够与吲哚杂环的共轭甲酰胺进行螺环丙烷化反应。开发的 In(OTf)3 催化方法提供了一种直接的、非对映选择性的方法，获得由 α-氰基和两个（杂）芳香族取代组装而成的药学相关的螺环丙烷-2-羟吲哚骨架。环丙烷化过程的常见困难，例如，共轭甲酰胺作为有效底物、酰胺键的裂解敏感性、底物范围仅限于优先含有吸电子基团的分子，以及由腈稳定的叶立德产生的产物的竞争性脱氢氰化反应在目前的螺环丙烷化方法中已被克服。