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-pyrazolaidoximes (3) with chloromethylated heterocyclic compounds (CICH2-R-3) 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, H-1 NMR, C-13 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 mu g/mL) as the commercial product Ningnanmycin (EC50 = 52.7 mu g/mL). To the best of our knowledge, this is the first report on the antiviral activity of pyrazole derivatives containing an oxime moiety.