Citric Acid-Catalyzed Three-Component Synthesis of (E)-3-Aryl-2-styryl-2,3-dihydroquinazoline-4(1H)-ones and Their Mild Oxidation with I2/DMSO System into (E)-3-Aryl-2-styrylquinazolin-4(3H)-ones

We hereby report a simple and efficient method for the preparation of (E)-3-aryl-2-styryl-2,3-dihydroquinazolin-4-(1H)-ones, from isatoic anhydride, anilines, and cinnamaldehydes in the presence of 20 mol% citric acid in methanol at 60 °C for 2 h. The styryl-dihydroquinazolin-4-(1H)-one products were obtained in moderate and good yields (30–80%) through the three-component condensation reaction, under an environment-friendly protocol. The latter were easily transformed into styrylquinazolin-4-(3H)-one derivatives with 57–91% yields using a mild oxidation with an I2/DMSO system for less than 60 min.