Nickel-Catalyzed Radical Hydroalkylative Dearomatization of Indoles with Alkyl Bromides

Abstract

Dearomatization of indole derivatives offers a straightforward approach to accessing indoline framework. However, highly efficient dearomatization of indoles bearing electron-deficient groups remains underdeveloped. Herein, a nickel-catalyzed intermolecular hydroalkylative dearomatization reaction of indoles with simple alkyl bromides via single-electron-transfer process is reported. A wide variety of indole derivatives bearing versatile functional groups were compatible with this protocol, by reacting with primary, secondary, and tertiary bromides to afford a series of indolines in good yields (up to 82%) with excellent diastereoselectivity (up to >20:1). Notably, a nickel-mediated hydrogen atom transfer process was observed when terminal bromides were employed as the radical precursors, which resulted in the branched products.