Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
Org Biomol Chem. 2020 Mar 4;18(9):1765-1768. doi: 10.1039/c9ob02751c.
An effective and operationally simple one-pot Brønsted acid catalyzed cascade method is demonstrated for the synthesis of diversely functionalized carbazole frameworks starting from protecting group free 2-alkenyl indoles. The employment of easily available unactivated ketones as annulating partners, mostly unexplored for the synthesis of carbazoles, is the major highlight of this protocol. This protocol is step- and atom-economical, uses molecular oxygen as the green oxidant, and gives water as the only by-product and is amenable to different functional groups. Moreover, gram-scale synthesis and downstream modification of the obtained products demonstrate the synthetic applicability of this protocol.
本文展示了一种有效且操作简单的一锅法 Brønsted 酸催化级联反应，可从无保护基的 2-烯基吲哚出发，合成各种官能化的咔唑骨架。该方法的主要亮点是使用易得的未活化酮作为稠合试剂，这在咔唑合成中大多未被探索过。该方法具有步骤经济性和原子经济性，使用分子氧作为绿色氧化剂，只生成水作为唯一的副产物，并且适用于不同的官能团。此外，克级规模的合成和获得产物的下游修饰证明了该方法的合成适用性。
