Synthesis and Bioactivities of Novel 1,2,4-Triazolo[1,5-a]pyrimidine Derivatives Containing 7-(1,3,4-Oxadiazolyl)thioether Moiety

Using 2-benzylthio-5-methyl-7-hydroxyl-1,2,4-triazolo[1,5-alpha]pyrimidine as starting material, ten novel 2-benzylthio-5-methyl-7-(5-substituted benzylthio-1,3,4-oxadiazol-2-yl)-methyleneoxyl-1,2,4-triazolo[1,5-a]pyrimidine derivatives 5a similar to 5j were synthesized via sequential reactions of etherification, hydrazinolysis, cyclization and thioetherification. The structures of target compounds were fully characterized by H-1 NMR, IR, MS and elemental analysis. The preliminary bioassay showed that some compounds possessed good anti-TMV (tobacco mosaic virus) or certain fungicidal activities in vitro. At the concentration of 500 mu g/mL, the inhibition rates of compounds 5b, 5f and 5j against TMV were 45%, 45% and 43%, respectively.