Synthesis and Biological Activities of Novel N-(2-(5-(3-Bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)-1,3,4-oxadiazol-2-yl)-4-chloro-6-methylphenyl) Amides

A series of novel aromatic amide compounds with N-pyridylpyrazole and 1,3,4-oxadiazole heterocyclic motifs were successfully synthesized with N-pyridylpyrazole carboxylic acid and 2-amino-3-methvlbenzoic acid as the starting materials, via multi-step reactions of nucleophilic addition, cyclization, acvlation, etc. The preliminary bioassay tests indicated that most of these compounds have apparent insecticidal activities, among which compounds N-(2-(5-(3-bromo-1-(3-chloro-pyridin-2-yl)-1H-pyrazol-5-yl)-1,3,4-oxadiazol-2-yl)-4-chloro-6-methylphenyl)acetamide (8a) and N-(2-(5-(3-bromo-1-(3-chloro-pyridin-2-yl)-1H-pyrazol-5-yl)-1,3,4-oxadiazol-2-yl)-4-chloro-6-methylphenyl)-3-chloro-2,2-dimethylpropanamide (8e) possessed a mortality rate of 70% towards Mythimna separata Walker at the concentration of 200 mg.L-1. Some of the compounds exhibited good fungicidal activities at 50 mg.L-1 against Sclerotinia sclerotiorum with the growth inhibitoly rates of 54.5%similar to 63.6%, which is more effective than the controls of triadimefon and chlorantraniliprole. Several compounds such as N-(2-(5-(3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)-1,3,4-oxadiazol-2-yl)-4-chloro-6-methylpheny Opivalamide (8f) and N-(2-(5-(3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)-1,3,4-oxadiazol-2-yl)-4-chloro-6-methylphenyl)-4-fluorobenzamide (8h) showed moderate fungicidal activity against Physalospora piricola. It is worth noting that compound 8e, which has favorable insecticidal and fungicidal activities towards Alythimna separata Walker and Scierotinia scierotiorum respectively, could be used as novel reference structure for new agrochemical hmovations.