Facile and efficient synthesis of quinazoline-2,4(1H,3H)-diones through sequential hydrogenation condensation

The heterocyclizations from various methyl (2-nitrobenzoyl)carbamates to substituted quinazoline-2,4(1H,3H)-diones under hydrogenation conditions were investigated in this study. In the presence of p-toluenesulfonic acid monohydrate in methanol, various quinazoline-2,4(1H, 3H)-diones were obtained in good to excellent yields within 12 h. The reaction was proposed to proceed through the cascade reactions of nitro reduction and condensation.