Synthesis of mesoionic 4-(para-substituted phenyl-5-2,4-dichlorophenyl)-1,3-4-thiadiazolium-2-aminides by direct cyclization via acylation of thiosemicarbazides

The synthesis of ten novel mesoionic 4-[para-substituted (H, CH3, OCH3, NO2, Cl, Br, OH, t-C4H9, C6H5, C4H9) phenyl-5-2,4-dichlorophenyl]-1,3-4-thiadiazolium-2- aminides, as hydrochlorides, are described. The synthesis strategy utilized the corresponding para-substituted isothiocyanates as starting materials to obtain the thiosemicarbazides through reaction with phenylhydrazine ( 61 - 98%), which were then submitted to acylation with 2,4- dichloro benzoyl chloride and direct cyclization to generate the desired substituted mesoionic compounds in good yields (ca. 80%).