An Efficient and Green Synthesis of 2,3-Dihydroquinazolin-4 (1H)-One Derivatives Catalyzed by {[BMIM]Methanesulfonate} Ionic Liquid

1-butyl-3-methyl imidazolium methanesulfonate ([Bmim] CH₃SO₃^–) ionic liquid catalyzed, an efficient method for the preparation of 2-phenyl-2,3-dihydroquinazolin-4(1H)-ones by the one-pot three-component cyclo condensation of isatoic anhydride, ammonium acetate and aromatic aldehydes in ethanol: water solvent system. This procedure has several advantages such as short reaction time, easy workup, excellent yields, and reuse of ionic liquid.