Design, synthesis and biological activities of 1,2,4-triazolo[1,5-a]pyrimidine-7-amine derivatives bearing 1,2,4-oxadiazole motif

Pyrimidine is an important heterocyclic ring with various activities, which are widely used in the field of pesticides and medicines. In this paper, a series of 1,2,4-triazolo[1,5-a]pyrimidine-7-amine compounds (V1-V16) containing 1,2,4-oxadiazole moiety were designed and synthesized. Their structures were confirmed by H-1 NMR, C-13 NMR, F-19 NMR, and HRMS. The biological activity results showed that compounds V5, V6, V7, V9, V10, V12, and V13 possessed good activity against Mythimna separate at 500 ppm, while compound V4 exhibited moderate activity against Aphis medicagini at 500 ppm. Furthermore, compounds V1 and V3 displayed good fungicidal activity against Pseudoperonospora cubensis at 200 ppm.