Design,Synthesis And Biological Activity Of Novel Pyrazole Amide Fungicide

The succinate dehydrogenase(SDH)is an essential functional component of the tricarboxylic acid cycle and the mitochondrial electron transfer chain.The organism will fail to produce ATP normally if the enzyme is inhibited,which eventually leads to the death of the organism.In recent years,more and more fungicide targeting SDH emerge.Due to unreasonable abuse,resistance problem develops fast.To solve this problem,designing and developing novel SDHI is a good solution.In this paper,two classes of 39 pyrazolamide compounds were designed and synthesized based on active substructure splicing method and silicon carbon replacement method.These compounds were characterized by 1H NMR,13C NMR and HRMS.Some representative compounds were characterized by X-ray crystal diffraction.Compounds can be classified to these two structure formulas:#12All the synthesized compounds were tested for the inhibition of enzyme activity.The results showed that the inhibitory activity of series Ⅱ were more active and superior to the control agents.For example,the testing results of compound 3-15-8(IC50＝0.083 μM)·compound 3-15-10(IC50=0.086 μM),compound 3-15-13(TC50=0.034 μM),and compound 3-15-16(IC50=0.046 μM),are better than the control agent Pydiflumetofen(IC50=0.13 μM)and Benzovindiflupyr(IC50=0.091 μM).All the synthesized compounds were tested for vitro fungicidal activity.The results showed that most of the compounds in series Ⅱ had a good performance in the control of soybean rust and 12 compounds entered further screening stage.We selected compound 3-15-2 and 3-15-8 to conduct the EC50 test for soybean rust due to their optimal prevention.And it turned out that compound 3-15-2 had a better result,which was 0.2121 mg/L.Thus,we conducted the field fungicidal activity experiment of soybean rust on compound 3-15-2.The result indicated that the compound possessed certain field fungicidal activity.The field fungicidal activity at a concentration of 100 mg/L is better than that of the control agent Azoxystrobin.