Synthesis of some new 3-(2'-heterocyclicethyl)-2-methyl-3,4- dihydroquinazolin-4-one derivatives as antimicrobial agents.

3-(2'-Chloroethyl)-2-methyl-3,4-dihydroquinazolin-4-one was reacted with acetylacetone, ethyl acetoacetate and diethylmalonate in the presence of sodium ethoxide to afford the alkylation products IV, V and VI. Compounds IV, V and VI were reacted with hydrazine hydrate, phenylhydrazine, hydroxylamine hydrochloride, urea and thiourea to yield 3-(2'-heterocyclicethyl)-2-methyl-3,4-dihydroquinazolin-4-on e derivatives VII-XV. The structures of the synthesized compounds were elucidated by elemental analyses and spectroscopic (IR and 1H-NMR) analyses. The prepared compounds were tested for their antimicrobial activities in comparison with tetracycline as a reference compound.