Abstract: The condensation  reaction of 2,4-dihydro-2-(2’-methyl phenylthioanilido)-5-methyl- 3H- pyrazol - 3- ones (1) and aromatic aldehydes in the presence of glacial acetic acid to give 4-arylmethylene-2,4-dihydro-2-(2’-methylphenylthioanilido)-5-methyl-3H-pyrazol-3-ones(2) . The synthesized compounds (2) reacted with urea/phenylurea in presence of alcoholic KOH at reflux temperature to give 1- (2’-methylphenylthioanilido) -3-methyl -4- aryl – 6 -imino/phenylimino -4,7- dihydro-1, 3- oxazino [5,4-d] pyrazoles (3). The synthesized compounds (3) have been screened for their bactericidal activities against bacteria S. aureus and B. subtilis at different concentrations.
 

Keywords : Pyrazolone, Oxazino-pyrazoles, Antibacterial activity of oxazino-pyrazoles.