Synthesis of Mesoionic 4-(para-Substituted Phenyl-5-2,4-dichlorophenyl)-1,3,4-thiadiazolium-2-aminides by Direct Cyclization via Acylation of Thiosemicarbazides.

Abstract 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%).