Discovery of a new fungicide by screening triazole sulfonylhydrazone derivatives and its downy mildew inhibition in cucumber

Abstract Downy mildew is a very important detrimental disease that lead reduced to fruits and vegetables. Due to the continuous growth of drug resistance, finding novel fungicides with dissimilar modes of function from present fungicides for controlling downy mildew are imminent. This work is an extension of our preceding research on the original triazole sulfonamide derivatives lead compound. Triazole sulfonamide as a remarkable nitrogen‐containing heterocyclic compound opposed cucumber downy mildew (CDM) develops a quite vital part in the sphere of the study of new farm chemicals. The existing report designs a certain amount of 1,2,4‐triazole‐1,3‐disulfonamide derivatives. Hydrazones have obtained extensive attention in the field of pharmaceutical due to its unique chemical structure and remarkable activity (insecticidal, antibacterial, antifungal and herbicidal). By means of coupling numerous hydrazone with triazole sulfonyl chloride groups, 24 novel derivatives were synthesized. Spectrum analysis of LC‐MS, 1 H NMR and 13 C NMR were used for characterizing these new compounds. Compared with commercial Cyazofamid using bioassays, most of these compounds displayed preferable fungicidal activities. Moreover, compounds 8q illustrated the greatest CDM resistance (EC 50 = 7.776 mg/L). Field efficacy trials revealed that compound 8q fungicidal activity was higher than the purchased agrochemical Cyazofamid and Amisulbrom. Thus, the research declared that 8q displayed a great potential for the application of fungicide against CDM.