A Na₂S₂O₈-mediated switchable oxidative cyclization of 4-arylquinoline-3-carboxamides is described. The catalyst-free reaction affords dibenzo[c,f][2,7]naphthyridinones in 32–78% yields in refluxing EtOAc/H₂O or CH₃CN/H₂O, while the AgNO₃-catalyzed reaction delivers spirocyclohexadienones in 25–72% yields in CH₃COCH₃/H₂O at room temperature.