An ultrafast (10 s) methodology to construct novel highly functionalized 2-quinolinones from N-(o-ethynylaryl)acrylamides (1,7-enynes) is described for the first time. Microwave irradiation enabled the ultrafast synthesis of 2-quinolinone-fused γ-lactones from Fenton's reagents in formamide. After six key consecutive reactions, including a diastereoselective step, 2-quinolinone-fused γ-lactones were obtained in good overall yield (up to 46%; 10 s).