N–N atropisomer synthesis via electrolyte- and base-free electrochemical cobalt-catalysed C–H annulation

Abstract

Merging electrochemistry with asymmetric C–H activation has proven to be an advantageous alternative to build valuable enantiopure molecules. However, established methods require a stoichiometric use of supporting electrolytes to promote the electron transfer in solution and often additionally serve as a base to assist C–H bond cleavage, which are hazardous and would produce additional waste. Herein, we described an exogenous electrolyte- and base-free electrocatalytic atroposelective C–H annulation, providing facile and sustainable access to N–N axially chiral isoquinolinones in excellent enantioselectivities and good yields. This protocol is enabled by a combination of simple Co(OAc)₂·4H₂O and readily available chiral salicyloxazoline (Salox), which proceeds well with 13 classes of alkynes, including highly challenging polarized either internal or terminal alkynes, and tolerates a wealth of functional groups for streamlined transformations.