Mechanism of the formation of 1,2,4-thiadiazoles by condensation of aromatic thioamides and of N-substituted thioureas

Article abstract of DOI:10.1002/jhet.5570370110

The condensation reaction of thiobenzamide, (as well as thionicotinamide and isothionicotinamide) in the presence of dimethyl sulfoxide and of an acid, affords 3,5-diphenyl-1,2,4-thiadiazole. Under the same experimental conditions, N-substituted thioureas are also condensed to 1,2,4-thiadiazole derivatives; their structure is ascertained by spectroscopic properties and by X-ray diffraction. Some information on the mechanism of thiadiazoles formation from both starting classes of compounds, thiobenzamides and N- substituted thiourea, is collected and discussed.