Various substituted 3-{6-fluoro-7-(substituted)-1,3-benzothiazol-2-yl-1 -[(4-acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)methyl]-2 -thioxo-2,3-dihydroquinazoline-4 (1H) -one and 3-{(6-fluoro -7- (substituted) - 1,3 -benzothiazol-2-yl-1-({4-acetyl-5-[4-(dimethylamino)phenyl]-4,5-dihydro -1,3,4-oxadiazol-2-yl}methyl) -2- thioxo -2,3- dihydroquinazolin -4 (1H)-one. containing different functional groups have been synthesized by condensing anthranilic acids with substituted 2-aminobenzothiazoles in dry pyridine and then by condensing with ethylchloroacetate in presence of dry acetone and K₂CO₃. The identity of compounds were confirmed on the basis of their spectral (UV, IR, ¹H NMR and MASS) data. Further, they have been screened for their antimicrobial activities.