An N-bromosuccinimide-catalyzed intermolecular annulation of acetyl indoles with alkynes was developed, allowing for regioselective formation of valuable carbazoles through direct C–H bond functionalization. The readily available catalyst, wide substrate scope, gram scale synthesis, and mild conditions make this method practical. Mechanistic investigations indicate that the bromination of acetyl indole takes place to generate a bromide intermediate, followed by coupling with an alkyne and intramolecular cycloaromatization to furnish carbazole products.

中文翻译：

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N-溴代琥珀酰亚胺（NBS）催化的CH键功能化：带有电子吸收基团（EWG）取代的乙酰吲哚的炔烃环化反应，用于合成咔唑

开发了一种N-溴代琥珀酰亚胺催化的炔烃与炔烃的分子间环化反应，可通过直接的CH键键合区域选择性地形成有价值的咔唑。易于获得的催化剂，广泛的底物范围，克级合成以及温和的条件使该方法实用。机理研究表明，发生乙酰基吲哚的溴化反应生成溴化物中间体，然后与炔烃偶联并进行分子内环芳构化以提供咔唑产物。