Abstract: Herbicides inhibiting protoporphyrinogen oxidase are one of the most important class of herbicides. Targeting the porphyrin pathway, these herbicides show high activity and low toxicity, and have been a hot-point of novel pesticides research. A series of novel substituted phenylpyrazole derivatives were prepared from 1′-(4-chloro-2-fluoro-5-methylphenyl)-4′,4′,4′-trifluoro-1,3-dibutanone via a ring closure reaction, methylation, chlorination, oxidization reaction and so on. The conditions of key steps were discussed. Their structures were confirmed by ¹HNMR, IR, CIMS and elemental analysis. Preliminary bioassay shows that these compounds have good herbicidal activity to latifoliate weeds, and their activity is better in soil treatment than in stem and leaf treatment.

Key words: Protoporphyrinogen oxidase inhibitor, Substituted phenyl pyrazole derivatives, Synthesis, Herbicidal activity