Synthesis and Antiviral Activities of Pyrazole Derivatives Containing an Oxime Moiety

Target compounds 4a−n were obtained by the reaction of 1-substituted phenyl-3-methyl-5-substituted phenylthio-4-pyrazolaldoximes (3) with chloromethylated heterocyclic compounds (ClCH2-R3) under reflux conditions in ethanol. Subsequently, the oxidation of 4a−e with KMnO4 in HOAc at room temperature afforded eight new compounds, 5a−h. The synthesized compounds were characterized by physical constants, and the structures of the title compounds were confirmed by IR, 1H NMR, 13C NMR, and elemental analysis. The bioassay revealed that the compounds possessed antiviral activities. It was found that title compounds 4a and 4g had the same inactivation effects against TMV (EC50 = 58.7 and 65.3 μg/mL) as the commercial product Ningnanmycin (EC50 = 52.7 μg/mL). To the best of our knowledge, this is the first report on the antiviral activity of pyrazole derivatives containing an oxime moiety.