Synthesis and Fungicidal Activity of 5-Aryl-1-(aryloxyacetyl)-3-(tert-butyl or phenyl)-4-(1H-1,2,4-triazol-1-yl)-4,5-Dihydropyrazole

A series of novel 5-aryl-1-(aryloxyacetyl)-3-(tert-butyl or phenyl)-4-(1H-1,2,4-triazol-1-yl)-4,5-dihydropyrazole 3a-3n were synthesized by the annulation of 2-aryloxyacetohydrazides with 3-aryl-1-t-butyl(or phenyl)-2-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones(1)in the presence of a catalytic amount of acetic acid.Compounds 2 were obtained by the Knoevenagel reactions of 1-t-butyl(or phenyl)-2-(1H-1,2,4-triazol-1-yl)ethanone(2)with aromatic aldehydes in the presence of piperidine.Their structures were confirmed by IR,1H-NMR,ESIMS,and elemental analyses.The preliminary bioassay indicated that some compounds displayed moderate to excellent fungicidal activity.For example,compounds 31,3m,and 3n possessed100%inhibition against Cercospora arachidicola Hori at the concentration of 50 mg/L.