Metal-free visible-induced C(sp2)–C(sp2) coupling of quinoxalin-2(H)-ones via oxidative cleavage of the C–N bond

Abstract

A C(sp²)–C(sp²) reaction between aromatic hydrazines and quinoxalines has been developed through a photocatalytic system. The protocol is established for C(sp²)–N bond cleavage and direct C(sp²)–H functionalization for the coupling of C(sp²)–C(sp²) via photocatalysis under mild and ideal air conditions without the presence of a strong base and metal. The mechanistic studies reveal that the generation of a benzene radical via the oxidative cleavage of aromatic hydrazines for the cross-coupling of C(sp²)–C(sp²) with the assistance of a photocatalyst is essential. The process exhibits excellent compatibility with functional groups and provides convenient access to various 3-arylquinoxalin-2(1H)-ones in good to excellent yields.