An efficient oxidative conversion of 2-aryl-2H-chromenes to the corresponding flavones by tert-butylhydroperoxide and copper bromide

•A simple and an efficient oxidative conversion of chromenes to flavones.•A very short reaction time and high level of functional group tolerance.•Non precious metal salt, Cu(II) bromide is used as a catalyst.•Wide applicability (21 examples) and good to excellent yields (67–94%).