Design, synthesis and antifungal activity of novel pyrazole amides derivates

With the help of active substructure splicing strategy, 36 novel pyridine ring pyrazolamide derivatives were designed and synthesized. The structures of those compounds were confirmed and characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. The compound 2i was identified by X-ray crystal diffraction. The fungicidal effects of the pyrazolamide derivates against four plant pathogenic fungi, Colletotrichum gloeosporioides, Fusarium oxysporum, Sphaeropsis sapinea and Fusarium moniliforme, was determined by the mycelial growth rate. The results showed that the designed compounds had certain antifungal activity at the concentration of 200 mg/L. Compared with the positive control carbendazim, compounds 1e, 1g and 1h exhibited stronger antifungal activity on Sphaeropsis sapinea and Fusarium moniliforme. The antifungal activity of compound 1a-1s (R1 = H) was better than that of compound 2a-2p (R1 = CH3). Compounds 1d, 1e, 1g, 1h, 1i, 2g and 2i showed good antifungal activity, and the introduction of halogen groups (except F) on benzene ring may have an important effect on biological activity. Compound 1g had a good inhibitory effect on the growth of a variety of plant pathogenic fungi. Molecular docking revealed that the -CH3 group at R1 position would reduce the binding affinity between these compounds and receptor, which would reduce the antifungal activity of the compound. Compound 1g is promising to become the lead compound of pesticide in the future, which is worthy of further study.