Synthesis And Biological Activities Of Pyrazole Derivatives

Pyrazole derivatives are widely studied in the world to find out new pesticide lead compounds. Based on the intermediates of tebufenpyrad(MK-239), 82 new compounds of pyrazole derivatives have been synthesized in three serials with the general formula as follows:Formular IX=NO2, H, Cl or Br, =2-thiazolidinone, 2-thiazolidinethione, 2-oxozolidinone, lH-3-methyl-2-pyrazolin-5-one, l.H-pyrazole-3-ethyl-5-carboxylic acid, ethyl ester, lH-imidazole or 1H-benzimidazole.The results of biological tests indicated that, at 25 μg/mL, 3-methyl-2-pyrazolin-5-one, l-[(3-ethyl-l-methyl-4-bromo-lH-pyrazole-5-yl)-carbonyl]- (TI-4-04) showed inhibitory activities (45.6%) against Pyricularia oryzae. At 500 μg/mL, 3-methyl-2-pyrazolin-5-one, l-[(3-ethyl-l-methyl-4-nitro-lH -pyrazole-5-yl)-carbonyl]-(TI-3-04) showed inhibitory activities (53.85%) against Nephotettix cincticeps. The crystal structure of TI-3-03 indicates that the dihedral angles is formed between the central link and the five-membered pyrazole and oxazolidin-2-one rings [planar to 0.079 (4) *10^-10 m] of 89.2 (2)° and 11.2 (2)°, respectively, and this fact is emphasized by the orthogonal relationship between the rings [dihedral angle =90.0 (2)°], which prove that the pyrazolyl-heterocycles can not be lead compounds.Foumular IIX=C1 or Br, R=C₁^C₈ alkyl, R₁=single replaced group, n=0 or 1.The results of fungicidal activity tests indicated that, 4-bromo-pyrazolyl-biacyl hydrazine might be lead compound. The results of insecticidal activity tests indicated that, 4-chloro-pyrazolyl-biacyl hydrazine might be lead compound.Foumular IIIX=Cl or Br, R=single or double replaced group.