Metal-Free, Redox-Neutral, Site-Selective Access to Heteroarylamine via Direct Radical–Radical Cross-Coupling Powered by Visible Light Photocatalysis

Abstract

Transition-metal catalyzed C-N bond-forming reactions have emerged as fundamental and powerful tools to construct arylamines, a common structure found in drug agents, natural products and fine chemicals. Reported herein is an alternative access to heteroarylamine via radical-radical cross-coupling pathway, powered by visible light catalysis without any aid of external oxidant and reductant. Only by visible light irradiation of a photocatalyst such as a metal-free photocatalyst, a cascade single electron transfer event of amines and heteroarylnitriles, manifested by steady-state and transient spectroscopic studies, results in amine radical cation and aryl radical anion in situ for the C-N bond formation. The metal-free and redox economic nature, high efficiency and site-selectivity of C-N cross-coupling of a range of available amines, hydroxylamines and hydrazines with heteroarylnitriles make this protocol promising in both academic and industrial settings.