Palladium-catalyzed annulative allylic alkylation for regioselective construction of indole-fused medium-sized cyclic ethers

Ling-Qi Chen,¹ Chi-Fan Zhu,¹ Su Zhang, Bao-Yang Liu, Shu-Jiang Tu,* Wen-Juan Hao,* Bo Jiang*

A new palladium-catalyzed annulative allylic alkylation (AAA) reaction of 2-(indol-2-yl)phenols with dual allylic electrophiles such as isobutylene dicarbonate and butene dicarbonate is described, leading to the regioselective synthesis of tetracyclic medium-sized cyclic ethers possessing a bridged aryl-indole scaffold, namely, benzo[2,3]oxocino[4,5-b]indoles and benzo[2,3]oxepino[4,5-b]indoles, in good to excellent yields. This protocol demonstrates a broad substrate scope, good compatibility with substituents and high regioselectivity, providing a catalytic and flexible method for creating bridged aryl-indole skeletons.

 Chin. Chem. Lett. 2023, 34, 108398; DOI: 10.1016/j.cclet.2023.108398