Synthesis and evaluation of in vitro biological activity of new series of quinazolinone and benzoxazinone derivatives

A convenient synthesis for 1,3,4-thiadiazolyl quinazolinone derivatives is described via facile cyclization of anthranilic acid with succinic anhydride and upon reaction with glycine afforded 3-glycinyl quinazolinone derivative (2), which then treated with thiosemicarbazide and produced 1,3,4-thiadiazolyl quinazolinone derivative (3). Also, the key intermediate isothiocyanatobenzoazinone (13) is synthesized and checked for the synthesis of triazolyl-(14), oxooxazolidinyl-(15) and triazinanyl-(16a,b) benzoxazinone scaffolds by reaction with phenylhydrazine, glycine and urea and/ or thiourea, respectively. Antimicrobial activity of the synthesized compounds were evaluated against selected bacterial and fungal strains and compared with penicillin and compounds 6, 7b, 10b, 11, 14 and 16b exhibited promising activity as compared to the tested standard. The structures of the products were assigned and confirmed on the basis of their elemental analyses as well as spectral data (IR, MS and H-1 NMR).