Sulfamic acid as a reusable and green catalyst for efficient and simple synthesis of 2-substituted-2,3-dihydroquinazolin-4(1H)-ones in water or methanol

A series of 2,3-dihydroquinazolin-4(1H)-ones have been synthesized in good to excellent yields through direct cyclocondensation of anthranilamide and aryl aldehydes or ketones in water or methanol under mild conditions. The reaction was efficiently promoted by 10 mol% sulfamic acid (SA, H2NSO3H) and the catalyst could be recovered easily after the reactions and reused without evident loss of reactivity.