Design, synthesis and insecticidal activity evaluation of novel oxime ether sulfonamide derivatives containing cyclopropane fragments against Plutella xylostella

Abstract BACKGROUND Plutella xylostella poses a severe threat to cruciferous crops globally and has evolved resistance to a broad spectrum of insecticides. This escalating resistance underscores an urgent need to develop novel insecticides with unique structures and distinct modes‐of‐action. RESULTS In this study, a series of oxime ether sulfonamide derivatives containing cyclopropane fragments were designed and synthesized using the alkyl oxime ether ethanesulfonamide compound ZY‐9 as the lead compound. Indoor insecticidal bioassay showed that compound 3a‐28 displays the greatest insecticidal activity against P. xylostella with a median lethal concentration (LC 50 ) value of 13.30 mg L –1 , which was comparable to those of the commercial insecticides diflubenzuron (13.90 mg L –1 ) and diafenthiuron (14.74 mg L –1 ). Synergism studies indicated that compound 3a‐28 presents a synergistic effect in combination with diafenthiuron, indoxacarb, chlorfenapyr and abamectin. Field trials demonstrated that compound 3a‐28 achieved 62.58% control efficacy, which was comparable to that of diafenthiuron. Morphological observation of the larvae revealed severe damage to the body surface, particularly to the setal sockets and epidermal collapse. Biochemical analysis results showed that compound 3a‐28 could increase the chitin content and inhibit the chitinase activity [Median inhibitory concentration (IC 50 ) = 14.10 mg L –1 ]. Molecular docking confirmed that compound 3a‐28 stably binds to the active pocket of chitinase ( Of ChtI). Additionally, preliminary toxicity evaluation results demonstrated that compound 3a‐28 exhibits excellent biosafety. CONCLUSION The novel cyclopropane‐containing oxime ether sulfonamide derivative 3a‐28 is a highly promising insecticide candidate against P. xylostella , featuring a unique chitinase‐inhibiting mechanism. The findings of this study lay a solid foundation for the future development of insecticides. © 2026 Society of Chemical Industry.