Copper-Catalyzed Cascade Preparation of Dihydropyrimidin-4-ones from N-(Prop-2-yn-1-yl)amides and Azides

Dihydropyrimidin-4-ones were efficiently synthesized from copper catalyzed reaction between N-(prop-2-yn-1-yl)amides and sulfonylazides under mild conditions in moderate to excellent yields (up to 96% yields). The cascade process involves the copper-catalyzed alkyne-azide cycloaddition, the formation of ketenimine intermediate, the intramolecular nucleophilic addition of ketenimine, and subsequent rearrangement.