Synthesis and Antimicrobial Activity of Newer Quinazolinones

2–alkyl–6–bromo–3,1–benzoxazine–4–one (2) is synthesized by treating p–Bromoanthranilic acid and Acetylechoride or Benzoylchloride. Reaction of 2–alkyl–6–bromo–3,1–benzoxazine–4–one (2). with hydrazinehydrate furnish the corresponding 3–Amino–2–methyl–6–bromoquinazoline–4(3H)–one (3) which on reaction with benzaldehyde afford N,N – arylidene derivative (4). Reaction of 4 with various diazonium salts yields 6–bromo–2–alkyl/aryl– 3{[phenyl(phenyldiazenyl)methylene]amino}quinazolin–4(3H)–one .


Introduction
Quinazoline nucleus possessed the potent pharmacodynamic nucleus.In addition several quinazoline derivatives posses diverse biological activities Viz.anticonvulsant 1 , hyponotics 2 , antiinflammatory 3,4 , diuretics antihypertensive 5,6,7 , antituberculor etc. quinazoline system posses variable sites at 2 and 3 positions substituted by various hetrocyclic moieties afford the potent anticonvulsant agent.Furthermore SAR study of different quinazolinone derivatives have revealed that the substitution at 3-position has significant role on hypotensive activity.

Experimental
All the melting points were determined in open capillary and are uncorrected.The purity is checked by TLC.IR Spectras were recorded in KBr on shimatzu F.T. -IR 8300 spectrophotometer.Analytical data were also confirmed from its H -NMR Spectra.

Results and Discussion
Synthesized compounds have been confirmed by elemental analysis, IR Spectra 1 HNMR Spectra.

Antibacterial Activity
The synthesized compounds were tested against gram positive bacteria staphylococcus aureus and Bacillus cereus and gram negative bacteria E. coli and Pseudomonas aeruginosa and a yeast candida albicans.The stock solutions of compounds were prepared at a concentration of 5mg/ml & from stock solution the disc were prepared at a concentration of 100µg/ml.The testing was done on muller hinton agar plates by swabbing the agar plates with respective cultures, and placing the disc on it and incubating at 37˚C for 24 hrs. the above results were obtained.
The compounds were also tested against mycobacterium tuberculosis at a concentration of 100µg/ml.The L.J. medium was prepared from dehydrated powder following the instructions given on the dehydrated medium bottle.The compound were then added into the medium in the desired concentration and then inspisated then the prepared L.J. medium was inoculated with the pure culture of mycobacterium tuberculosis and incubated at 37˚C for 7 weeks and then the results were read.
Standard drug tetracycline and Greseofulvin were also screened under similar conditions for comparison.Results are shown in Table 3.

Table 3 .
Antimicrobial Activity of Newly Synthesised Compounds, Zone of Inhibition (Mm)