Synthesis, structure and herbicidal activity of substituted phenyl pyrazole derivatives

摘要

To search for novel Protox inhibitors, a series of phenyl and 1,4-benzoxazin-5-yl pyrazole derivatives were synthesised from 3-(4-chloro-2-fluoro-5-methoxyphenyl)-1-methyl-5-trifluoromethyl-1 H -pyrazole or its halogen substituted derivatives, via a serial of reactions that included nitration, reduction, acetylation, ring closure, methylation, etc. The single crystal of 2-(N-acetylacetamido)-6-chloro-3-[4-chloro-5-(trifluoromethyl)-1-methyl-1H -pyrazol-3-yl]-4-fluorophenyl acetate was prepared, and its structure was determined by X-ray analysis. The preliminary bioassay test shows that some of the compounds have high bioactivity. Especially, even at a low dosage of 150 g hm~(-2), 2-(N-acetylacetamido)-6-chloro-3-[4-chloro-5-(trifluoromethyl)-1-methyl-1 H -pyrazol-3-yl]-4-fluorophenyl acetate exhibited high activity, the inhibiting rate for both of the weeds reached above 90%.