Synthesis and isomerization of enone oximes and their biological activity

Corn rust and rice sheath blight are two major crop diseases of global importance, and hence there is much focus on solving problems regarding their control. The synthesis, isomerization, biological activity of enone oximes, the key intermediate in the synthesis of Strobilurin fungicides, and the fungicidal mechanism were researched. This study will guide the development and application of new, highly active Strobilurin fungicides.

Enone oximes are synthesized using 2,6-dichlorobenzylideneacetone and hydroxylamine hydrochloride as the primary raw materials. A kinetic model for the synthesis reaction of enone oxime was established based on thermodynamic and kinetic analyses, the reaction order of 2,6-dichlorobenzylideneacetone, hydroxylamine hydrochloride and sodium hydroxide are 0.365, 0.395 and 1.085, respectively. The activation energy of the reaction was 44.32 kJ mol^-1, and the apparent reaction heat was 80.94 kJ mol^-1. Single crystals of E-enone oxime and Z-enone oxime were prepared, and their absolute configurations were determined by single-crystal X-ray diffraction. An isomerization strategy was developed by using gaseous hydrogen chloride as a catalyst, enabling the conversion of Z-enone oxime to E-enone oxime through a protonation-rotation mechanism. The cytochrome b protein (RsCytb) of the rice sheath blight pathogen Rhizoctonia solani was selected as the target protein, and its structure was modeled using AlphaFold₃ before molecular docking.

Directed synthesis of the highly active E-enone oxime was successfully achieved, and its mechanism as a highly active fragment and bioactive scaffold was clarified. E-enone oxime would be a promising bioactive fragment and active scaffold of Strobilurin fungicides. © 2026 Society of Chemical Industry.