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]-2
H-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. Phytotoxic activities against
Echinochloa crus-galli L.
, Digitaria ciliaris L.,
Brassica napus L. and
Chenopodium serotinum L. were evaluated by the culture dish method. Preliminary bioassay results indicated that some target compounds exhibited good phytotoxic activity at a dose of 100 mg/L, with an inhibitory rate of 76.0–85.6% on root growth, even higher than the control herbicide, fenoxaprop-P-ethyl.
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