Metal-free Visible-Induced C(sp2)-C(sp2) Coupling of Quinoxalin-2(H)-ones Via Oxidative Cleavage of the C-N Bond.

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.