Synthesis and fungicidal activities of [2-(2,5-dimethylphenoxymethyl)-alpha-methoxyiminobenzyl]-isoxazole derivatives

A series of [2-(2, 5-dimethylphenoxymethyl)-alpha-methoxyiminobenzyl]isoxaz ole derivatives were synthesized and their fungicidal activities against cr op diseases were assessed. Our studies of the structure-activity relationsh ips revealed that fungicidal activities against cucumber powdery mildew and wheat powdery mildew were the strongest when the isoxazole moiety was comp rised of 4,5-dihydro-3-isoxazolyl, 3-isoxazolyl and 3-methyl-5-isoxazolyl g roups. Of the two geometrical isomers at the oxime moiety, the E-isomers of non-substituted isoxazole derivatives were more active than the Z-isomers, On the other hand, the Z-isomers of methyl-substituted isoxazole derivativ es were more active than the E-isomers. Further, [2-(2,5-dimethylphenoxymet hyl)-alpha-methoxyiminobenzyl] isoxazole derivatives exhibited highly poten t respiratory inhibition.