Synthesis and fungicidal activities of heterocyclic compounds having alpha-methoxyimino-2-phenoxymethylbenzyl group

A series of (alpha-methoxyimino-2-phenoxymethylbenzyl) heterocycle derivati ves were synthesized and their fungicidal activities were assessed. Studies of the structure-activity relationships revealed the strongest fungicidal activity when the heterocycle moiety was comprised of 1-methyl-2-imidazolyl and 1,3,4-oxadiazol-2-yl groups. When the benzene ring on the phenoxymethy l moiety was substituted with 2-methyl, 2,5-dimethyl or 4-chloro-2-methyl, good fungicidal activity was obtained. Between the two geometrical isomers at the oxime moiety, the E-isomers of imidazole and oxadiazole derivatives were more active than the Z-isomers. Among the compounds examined, (E)-2-[2 -(4-chloro-2-methylphenoxymethyl)-alpha-methoxyiminobenzyl]-1-methylimidazo le (27) showed a potent activity against cucumber powdery mildew and cucumb er gray mold.