Visible-Light Promoted Regioselective Oxygenation of Quinoxalin-2(1 H )-ones Using O 2 as an Oxidant.

A visible-light-mediated sustainable approach for metal-free oxygenation of quinoxalin-2(1 H )-one by employing Mes-Acr-MeClO 4 as a photocatalyst without using any additive or cocatalyst is reported here. O 2 served as the eco-friendly and green oxidant source for this conversion. In addition, the protocol exhibited high regioselectivity and tolerance toward a broad spectrum of functional groups to furnish quinoxaline-2,3-diones in good to excellent yields.