Convenient synthesis and antibacterial activity of novel 5-phenyldiazenyl-1,3,4-thiadiazole derivatives

Reaction of N,2-diaryldiazene-1-carbohydrazonoyl chlorides 1, 2 with 2-((methylthio)-carbonthioyl)hydrazones 7, 12 and 18-21 in absolute ethanol at room temperature in the presence of triethylamine afforded the corresponding 1,3,4-thiadiazole derivatives 10, 11, 13, 14 and 22-29. Stirring of N,2-diaryldiazene-1-carbohydrazonoyl chlorides 1-3 with thioanilides 31A-E in acetonitrile at room temperature in the presence of triethylamine gave the corresponding 1,3,4-thiadiazol-2(3H)-ylidene derivatives 34-36. The structures of all new compounds 10, 11, 13, 14, 22-29 and 34-36 were identified by elemental analysis and spectral data. Some new synthesized compounds were studied against Staphylococcus aureus and Escherichia coli and the most potent compounds were 3-phenyl-5-(phenyldiazenyl)-2-((1-(pyridin-2-yl)ethylidene)hydrazono)-2,3-dihydro-1,3,4-thiadiazole (13c), 2-((1-(pyridin-2-yl)ethylidene)hydrazono)-3-(p-tolyl)-5-(p-tolyldiazenyl)-2,3-dihydro-1,3,4-thia-diazole (14c) and 2-(benzo[d]thiazol-2-yl)-2-(3-(p-tolyl)-5-(p-tolyldiazenyl)-1,3,4-thiadiazol-2(3H)-ylidene)-acetonitrile (35C).