Synthesis and Fungicidal Activity of Novel 2,5-Disubstituted-1,3,4-oxadiazole Derivatives

A novel series of 1,3,4-oxadiazole derivatives containing a 5-phenyl-2-furan moiety were synthesized from the intermediates diacylhydrazine 3 and acylhydrazone 5 via an efficient approach under microwave irradiation in good yields. Their structures were characterized by IR, H-1 NMR, and elemental analysis. The antifungal tests indicated that the title compounds showed in vivo fungicidal activity against Botrytis cinerea and Rhizoctonia solanii at 500 mu g/mL obviously. Some tested compounds even had a superiority effect over the commercial fungicides 40% Pyrimethanil SC and 3% Validamycin AS. The activity between the title compound and their precursors diacylhydrazine 3 and acylhydrazone 5 was also compared and discussed.