A novel deamination of 2-alkyl/aryl 3-amino-4(3H)-quinazolinones series using aqueous KMnO4 under thermal condition and microwave irradiation is described. Compared to thermal condition, significantly higher yields in much shorter times were observed for reactions under microwave irradiation. A plausible mechanism has been proposed for the oxidative water-promoted deamination. A novel deamination of 2-alkyl / aryl 3-amino-4 (3H) -quinazolinones series using aqueous KMnO4 under thermal condition and microwave irradiation is described. Compared to significantly higher yields in observed fewer times were reactions under microwave A plausible mechanism has been proposed for the oxidative water-promoted deamination.