Synthesis and antifungal activity of novel pyrazolecarboxamide derivatives containing a hydrazone moiety

Background: The plant pathogenic fungus (such as Gibberella zeae, Fusarium oxysporum and Cytospora mandshurica) causes devastating disease in agriculture. The pathogenic fungus is responsible for billions of dollars in economic losses worldwide each year. In order to discover new fungicidal molecule with good fungicidal activity against G. zeae, F. oxysporum, and C. mandshurica, we sought to combine the active sub-structure of hydrazone and pyrazole amide derivatives together to design and synthesize novel pyrazole amide derivatives containing a hydrazone moiety. Results: A series of novel pyrazole amide derivatives bearing hydrazone moiety were synthesized. Their structures were characterized by H-1-NMR, C-13-NMR, IR, and elemental analysis. The preliminary biological assays revealed that most of the synthesized compounds exhibit favorable antifungal activities against G. zeae. The activity of compounds 7a, 7f, 7g, 7h, 7i, 7j, 7l and 7q were 40.82%, 47.78%, 50.32%, 40.82%, 49.05%, 48.73%, 40.19% and 45.89%, respectively, and the synthesized compounds showed certain antifungal activities against F. oxysporum and C. mandshurica. Conclusion: A practical synthetic route to pyrazole amide derivatives containing a hydrazone moiety were synthesized by the condensation of intermediates 5-chloro-N-(4-subsititued-2-(hydrazinecarbonyl)-6-methylphenyl)-1,3-dimethyl-1 H-pyrazole-4-carboxamide with different aldehydes or ketones in ethanol at room temperature is presented, the results of the study suggested that the pyrazole amide derivatives containing hydrazone moieties could inhibit the growth of G. zeae, F. oxysporium and C. mandshurica to a certain extent.