Structure and fungicidal activities of 2-methoxyimino-N-methyl-2-[2-(substituted pyridyloxymethyl)phenyl] acetamide derivatives

摘要

A number of 2-methoxyimino-N-methyl-2-[2-(substituted 2-pyridyloxymethyl)phenyl] acetamides were synthesized and their fungicidal activities were examined. The activities and fungicidal spectra of the derivatives varied markedly depending upon the substituents on the pyridine ring. Incorporation of either 1 or 2 substituent(s) at the 3-, 5- and/or 6-positions of the pyridine ring resulted in an increase in fungicidal activity compared with the unsubstituted compound. Among the 2-pyridyl derivativessynthesized in this study, 3-CF3-5-Cl, 5-CF3-3-Cl and 3-CF3-6-Cl derivatives exhibited the strongest preventive and curative activities against rice blast (Magnaporthe grisea), wheat powdery mildew (Erysiphe tritici), cucumber grey mould (Sphaerotheca fuliginea)and cucumber downy mildew (Botrytis cinerea). 3,5,6-Tri-substituted derivatives demonstrated strong preventive and curative activities against cucumber and wheat powdery mildew, however, they exhibited excellent preventive but weak curative activities against cucumber downy mildew. Between the 2 geometrical isomers, the E-form exhibited stronger activity than the Z-form.