C(sp3 )-H Cyanation Promoted by Visible-Light Photoredox/Phosphate Hybrid Catalysis

Abstract

Inspired by the reaction mechanism of photo-induced DNA cleavage in nature, a C(sp³ )-H cyanation reaction promoted by visible-light photoredox/phosphate hybrid catalysis was developed. Phosphate radicals, generated by one-electron photooxidation of phosphate salt, functioned as a hydrogen-atom-transfer catalyst to produce nucleophilic carbon radicals from C(sp³ )-H bonds with a high bond-dissociation energy. The resulting carbon radicals were trapped by a cyano radical source (TsCN) to produce the C-H cyanation products. Due to the high functional-group tolerance and versatility of the cyano group, the reaction will be useful for realizing streamlined building block syntheses and late-stage functionalization of drug-like molecules.

Keywords: C−H activation; cyanation; late-stage functionalization; phosphoric acid; photoredox catalysis.