SYNTHESIS AND INSECTICIDAL ACTIVITY OF 1-(5-(BENZYLTHIO)-1,3,4-THIADIAZOL-2-YL)-3-(ALKYL, ARYL)THIOUREAS

1,3,4-Thiadiazole derivatives exhibit a broad spectrum of biological activities. Indeed, several well-known biologically active compounds have been developed based on this scaffold, including the diuretic acetazolamide, the antibiotics sulfamethizole and cefazolin, the antidepressant atibeprone, and the broad-spectrum herbicides ethidimuron and buthidazole. As part of our ongoing research on the chemical transformations of previously synthesized 5-amino-1,3,4-thiadiazole-2-thione derivatives [1], we investigated the reactions of 2-(benzylthio)-5-amino-1,3,4-thiadiazole (1) with butyl and aryl isothiocyanates (aryl = C6H4-3-Br, C6H4-4-F, and C6H4-4-Cl). As a result, 1-(5-(benzylthio)-1,3,4-thiadiazol-2-yl)-3-(alkyl, aryl)thioureas (2–5) were obtained in good yields (75–83%). The optimal reaction conditions were found to be stirring in DMF in the presence of KOH at room temperature (20-25°C) for 5 h.The chemical structures of the synthesized compounds were confirmed by IR, №H NMR, and №іC NMR spectroscopy. The insecticidal activity of the synthesized compounds was evaluated against Spodoptera frugiperda and Helicoverpa zea cells. Compounds 2-5 exhibited significant activity against S. frugiperda cells, producing mortality/inhibitory effects of 62-83% and 11-81% at concentrations of 100 and 10 мM, respectively. In contrast, their activity against H. zea cells was lower, with mortality/inhibitory effects ranging from 58-75% and 0-70% at the same concentrations. Among the tested compounds, 1-(5-(benzylthio)-1,3,4-thiadiazol-2-yl)-3-(4-chlorophenyl)thiourea (4) demonstrated the highest activity against S. frugiperda cells, with inhibitory effects of 83% and 81% at 100 and 10 мM, respectively. Meanwhile, 1-(5-(benzylthio)-1,3,4-thiadiazol-2-yl)-3-(3-bromophenyl)thiourea (5) showed the highest activity against H. zea cells, reaching 75% and 70% at the corresponding concentrations.

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