Synthesis of 2-Heteroquinazolin-4-(3H)-ones via Palladium Catalysis

Significance

Reported is a simple and efficient strategy for the one-step synthesis of 2-heteroquinazolin-4-(3H)-ones 3 involving palladium-­catalyzed intermolecular nucleophile 2 addition to carbodiimide 1 followed by an intramolecular cyclocarbonylation reaction. After optimization of the reaction conditions, it was demonstrated that the reaction system is not sensitive to solvent and pressure of CO. The scope of this reaction was extended to a variety of carbodiimides (with EDGs and EWGs) and nucleophiles (cyclic and acyclic secondary amines, secondary anilines, phenols) to afford products 3 in moderate to good yields. However, thiol nucleophiles were found not to participate in the reaction. A plausible mechanism was proposed without evidence.