SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF SOME 1,3,4-OXADIAZOLES AND THIAZOLIDINONES

5-p-Chlorophenylamino-2-mercapto-1,3,4-thiadiazole was refluxed with HCHO and NH(4)Cl to yielded 5-p-chlorophenylamino-3-aminomethyl-2-mercapto-1,3,4-thiadiazole (I). The Mannich base (I) was treated with substituted aromatic esters to give 3-aminomethyl-[5-(p-chlorophenylamino)-2-mercapto-1,3,4-thiadiazole-5-yl]-methyl benzoate (IIa)/4'-(2',6'-dinitrophenoxy-ethylacetate) (IIb). The esters (IIa-b) on hydrazinolysis yielded 3-aminomethyl[5-(p-chlorophenylamino)-2-mercapto-1,3,4-thiadiazol-5-yl]-benzoic acid hydrazide (IIIa)/4'-(2',6'-dinitro phenoxy)-acetyl hydrazide (IIIb). The compounds (IIIa-b) in presence of POCl(3) with appropriate aromatic acids underwent cyclization to give 2-(aryl/2 '',4 ''-substituted aryl)-3-[3'-aminomethylphenyl-5'-(p-chlorophenylamino)-2'-mercapto-1',3',4'-thiadiazol-5'-yl]-1,3,4-oxadiazoles (IVa-d) and 2-(3 '',5 ''-dinitrophenyl)-[3'-aminomethyl {2''', 6'''-dinitrophenoxy acetyl}-5-p-chlorophenyl amino-2'-mercapto-1',3',4'-thiadiazol-5'-yl]-1,3,4-oxadiazole (IVe). In other set of reaction, aromatic hydrazides (IIIa-b) were treated with appropriate aromatic aldehydes to give Schiff bases namely, 3'-aminomethyl-5'-(p-chlorophenylamino)-2'-mercapto-1',3',4'-thiadiazol-5'-yl]-phenyl-amido-(4 ''-hydroxy)-benzylidene imine (Va)/2 '',6 ''-dinitrophenoxymethylamido-(2'''/3''',4'''-substituted aryl)-benzylidene imines (Vb-d). Va-d were then reacted with thioglycollic acid to yield thiazolidinones namely 3-[3'-aminomethyl-5'-{p-chlorophenylamino}-2'-mercapto-1',3',4'-thiadiazol-5'-yl]-phenylamido -2-(p-hydroxyphenyl)-4-thiazolidinone (VIa)/2 '',6 ''-dinitrophenoxymethylamido-2-(2'''/3''', 4'''-substituted aryl)-4-thiazolidinones (VI-b-d).