Abstract
Eight N-[3-(2,4-dichlorophenyl)-5-methylisoxazol-4-ylcarbonyl]-N′-(4,6-disubstituted pyrimidin-2-yl)thioureas and eight 5,7-disubstituted-2-[3-(2,4-dichlorophenyl)-5-methyl isoxazol-4-ylcarbonylimino]-2H-1,2,4-thiadiazolo[2,3-α]pyrimidines were synthesized by multi-step reactions in yields of 50–85%. The structures of the target compounds were confirmed by IR, 1H NMR spectra and elemental analyses. Herbicidal activities against Echinochloa crusgalli L., Digitaria ciliaris L., Brassi canapus L. and Chenopodium serotinum L. were also evaluated by the culture dish method. Preliminary bioassay results indicated that some target compounds exhibited good herbicidal activity at a dose of 100 mg/L, with an inhibitory rate of 76.0–85.6%, even higher than the control herbicide, fenoxaprop-p-ethyl.
