Design, Synthesis, and Bioactivity Evaluation of Novel 3‐(Substituted Phenoxy)‐6‐Methyl‐4‐(3‐Trifluoromethylphenyl) Pyridazine Derivatives

Using 3-(4-cyano phenoxy)-6-methyl-4-(3-trifluoromethylphenyl) pyridazine (compound ) as a leading compound, a total of 24 novel 3-(substituted phenoxy)-6-methyl-4-(3-trifluoromethylphenyl) pyridazine derivatives containing two electron-withdrawing groups on the benzene ring (acylamine and oxime ether) were synthesized. Their herbicidal, insecticidal activities were bioassayed, and the herbicidal activity of compound against Brassica campestris was 97.6% at 300 g/ha, which was better than the commercial herbicide diflufenican at the this concentration and is equal to the activity of the leading compound . Compound , , , and displayed excellent insecticidal activity against Aphis laburni Kaltenbach (>95%). The results show that the oxime ether substitutions exhibit better bleaching and herbicidal activity than the acylamine ones. The bleaching and herbicidal activity of para-position substitutions is better than the meta-position ones. It seems that the para-position on the benzene ring of oxime ether pyridazine derivatives is one of the key active sites that affect their herbicidal activities.