Synthesis and Fungicidal Activities of Heterocyclic Compounds Having α-Methoxyimino-2-phenoxymethylbenzyl Group

A series of (α-methoxyimino-2-phenoxymethylbenzyl) heterocycle derivatives 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 phenoxymethyl 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)-α-methoxyiminobenzyl]-1-methylimidazole (27) showed a potent activity against cucumber powdery mildew and cucumber gray mold.