Synthesis and Fungitoxicity of 3,5-Disubstituted Isoxazoles

Twenty isoxazoles were synthesized from α, ß-unsaturated carbonyl compounds and evaluated against Pythium aphanidermatum and Fusarium oxysporum. Compared to quintozene, the reference fungicide (ED₅₀ 141 mg l⁻¹), effective dosage for 3-phenyl-5-(4-methoxyphenyl) isoxazole, 3-(2-chlorophenyl)-5-(4-nitrophenyl) isoxazole, 3-(4-nitrophenyl)-5-(4-methoxyphenyl) isoxazole and 3,4-methlenedioxy phenyl-5-methylisoxazole against P. aphanidermatum were less than 100 mg l⁻¹. Against F. oxysporum 3-(3-nitrophenyl)-5-(4-methoxyphenyl) isoxazole with ED₅₀ value of 4S6.6 mg l⁻¹ was found to be most potent among the test chemicals.