A facile and convenient synthesis of 1,3,4-thiadiazolyl quinazolinone derivatives is described via cyclization of anthranilic acid with maleic anhydride, which upon reaction with glycine afforded 3-glycinyl quinazolinone derivative (2), then treated with thiosemicarbazide and produced 1,3,4-thiadiazolyl quinazolinone derivative (3). Moreover, benzoxazinone isothiocyanate (13) is used as a key compound in synthesizing of triazolyl-(14), oxazolidinyl-(15) and triazinanyl-(16a,b) benzoxazinone heterocycles by reaction with phenyl hydrazine, glycine and urea and/ or thiourea, respectively.
Evaluation of antimicrobial activity of some of the synthesized compounds against selected bacteria and fungi strains in comparison with Ampicillin as antibacterial agent and Amphotericin B as antifungal agent exhibited promising activity as compared to the references. The structures of the synthesized compounds were confirmed on the basis of their elemental analyses as well as spectral data (IR, MS and 1H NMR).