Syntheses, antibacterial and antifungal activities of substituted -thiazolo - 1.3.4-thiadiazoles, 1,3,4-oxadazoles and 1,2,4-triazoles

Starting from readily available 2-substituted-4-methylthiazole-5-carboxylic acid hydrazide (1), The title compounds were prepared. The reaction ofcompound 1 (R=CH3) with formic acid yielded 1-(formyl)-2-(2,4-dimethylthia-zole-5-carboxyl) hydrazine (2). Refluxing the latter with phosphorous pentasulfidein xylene afforded compound 3, the reaction of compound 2 with phosphorous pen-toxide afforded compound 4. Reaction of compound 1 with substituted isothio-cyanates followed by cyclization of the intermediate 5 in basic medium gave 4-alkyl-5-(2- substituted-4-methyl-5-thiazolyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione(6). Alkylation of compound 6 followed by subsequent oxidation of intermediate7 gave compound 8. The reaction of acid chloride 11 with hydrazide 12 affordedcompound 13 which was cyclized by P2S5 or P2O5 to compounds 14 or 15 respec-tively. Compounds 3 and 14 showed significant activities against E. Coli andBacillus Subtilis.