Synthesis and biological evaluation of some novel triazolo, thiadiazole derivatives of gallic acid.

In the present study, a new series of 5-{6-(substituted phenyl)-5,6-dihydro-(1,2,4) triazolo(3,4- b)(1,3,4)thiadiazol-3-yl}benzene-1,2,3-triol 7a-j have been synthesized. The reaction of Propyl gallate 1 and hydrazine hydrate 2 yielded galloylhydrazide 3,which on treatment with potassium hydroxide and carbondisulfide furnished 5-(-5-mercapto-1,3,4-oxadiazol-2-yl) benzene-1,2,3- triol 4 .This on hydrazinolysis gave 5-(4-amino-5mercapto - 4H-1,2,4 – triazol-3-yl) benzene - 1,2,3-triol 5. Finally cyclization of 5 with various aromatic aldehyde 6a-j and piperidine converted into the title compounds 7a-j. These compounds have been characterized by IR, 1HNMR, Mass spectral analysis. These newly synthesized compounds were screened for their antimicrobial activity and anti-inflammatory. The anti-inflammatory activity has been done by carrageenan induced acute paw oedma in rats. The in vitro antimicrobial activity has been carried out by cup plate method and minimum inhibitory concentration value was determined for the titled compound by agar streak dilution method.