Potential new fungicides: N-acyl-5-methyl-3(2H)-isoxazolone derivatives

Various 2-N-acyl-5-methylisoxazolone derivatives were prepared, and their antifungal activities were evaluated in vitro with mycelial growth inhibition tests. In contrast with N-alkyl derivatives, the acyl compounds showed significant activity against Pyrenophora graminea, Fusarium graminearum, Alternaria alternata, Cercospora beticola, Rhynchosporium secalis, Septoria tritici, Microdochium nivale, Rhizoctonia solani and Gaeumannomyces graminis.Of note, cinnamoyl, 3-furan-3-ylacryloyl- and 3-thiophen-3-yl-acryloylamides, and t-butylacetyl and pivaloyl derivatives showed high inhibition rates at 25 mg/L against R. solani and G. graminis, respectively.