No abstract

To discover new potential insecticides to protect agricultural crops from damage, a series of novel flupyrimin derivatives containing an arylpyrazole core were designed and synthesized. Their structures were confirmed by 1H NMR, 13C NMR, and HRMS. Bioassays indicated that the 31 compounds synthesized possessed excellent insecticidal activity against Plutella xylostella. Among these target compounds, the lethality of A3, B1-B6, D4, and D6 reached 100% at 400 μg/ml. Moreover, when the concentration dropped to 25 μg/ml, the insecticidal activities against the Plutella xylostella for compounds B2, B3, and B4 still reached more than 70%. The structure–activity relationship of the Plutella xylostella was discussed. The density functional theory analysis of flupyrimin and B4 was carried out to support the abovementioned structure–activity relationship. The possible binding modes between receptor and active groups in title compounds were also verified by docking simulation. These results provided new ideas for the development of these novel candidate insecticides in the future.

During our previous research using natural product phenazine-1-carboxylic acid as the lead compound to develop new pesticides, the phenazine-1-methanol had been found to exhibit excellent fungicidal activity. According to the above fact, a new class of phenazine-1-aryl(5-pyrimidine)methanol derivatives were designed and synthesized by using phenazine-1methanol as a secondary lead compound, and referring to ergosterol biosynthesis inhibitor fenarimol. The bio-assays showed that compounds 6a～6p displayed moderate fungicidal activities against Thanatephorus cucumeris and Phytophthora capsici. An interesting result is that the fungicidal activities of some of the target compounds against Phenazine-1-carboxylic-Acid (PCA) specific spectrum Thanatephorus cucumeris are greatly reduced, while against fenarimol characteristic spectrum wheat powdery mildew (Erysiphe graminis) retain moderate or strong control effects. The above bio-assays results indicated the mode of action of compounds 6a～6p may be different from that of PCA, but similar to fenarimol. Therefore, further ergosterol biosynthesis inhibition experiment proved that the target compounds had the same mode of action as commercially available fungicide fenarimol.