Syntheses, Antibacterial and Antifungal Activities of Substituted-Thiazolo-1,3,4-Thiadiazoles, 1,3,4-Oxadiazoles and 1,2,4-Thiazoles

Starting from readily available 2-substituted-4-methylthiazole-5-carboxylic acid hydrazide (1), The title compounds were prepared. The reaction of compound 1 (R=CH3) with formic acid yielded 1-(formyl)-2-(2,4-dimethylthiazole-5-carboxyl) hydrazine (2). Refluxing the latter with phosphorous pentasulfide in xylene afforded compound 3, the reaction of compound 2 with phosphorous pentoxide afforded compound 4. Reaction of compound 1 with substituted isothiocyanates followed by cyclization of the intermediate 5 in basic medium gave 4-alkyl-5-(2-substituted-4-methyl-5-thiazolyl)-,4-dihydro-3H-1,2,4-triazole-3-thione (6). Alkylation of compound 6 followed by subsequent oxidation of intermediate 7 gave compound 8. The reaction of acid chloride 11 with hydrazide 12 afforded compound 13 which was cyclized by P2S5 to compounds 14 or 15 respectively. Compounds 3 and 14 showed significant activities against E. Coli and Bacillus Subtilis.