Study On Synthesis And Antifungal Activity Of Benzimidazolyl-contaning Pyrazole Hydrazone Derivatives

Based on the structure characteristics, benzimidazole derivatives manifest a variety ofbiological activities and are widely used in medicine, pesticides and other fields，such asantibacterial, antitumor and antianxiety. Many compounds contain pyrazole groups showexcellent antibacterial, insecticidal, weeding and other biological activities. As for thegroups on the pyrazole ring could be changed by different methods, the pyrazole derivativesalways show high efficiency, low toxicity and are widely used in the field of pesticide.Hydrazone derivatives,a special kind of Schiff Base, show excellent biological,pharmacological activities and strong coordination ability, so they show great researchpotential in the field of pesticide, medicine and functional materials. In this research a seriesof benzimidazolyl-contaning pyrazole hydrazone derivatives were designed and synthesizedbased on the association principle in order to find out a bacteriostatic agent with goodbiological activity.In this research, parent compound6a was synthesized from the raw materials such asethyl cyanoacetate, triethyl orthoformate and o-phenylendiamine by the steps ofcondensation, cyclization, substitution and hydrazinolysis. Then6a was condensed withdifferent kinds of aromatic aldehyde compounds to obtain20unreported target compounds.The structures of these20compounds had been confirmed by the methods of1H NMR,MSand IR.The antifungal activity of the parent compound6a and20benzimidazolyl-contaningpyrazole hydrazone derivatives were tested by means of mycelium growth rate methodunder the concentration of50mg/L. The commercial fungicides Probenazole andAzoxystrobin acted as the positive controls in the test. The testing strains are Curvularialunata, Magnaporthe oryzae, Cytospora mandshurica, Alternaria oleracea, Fusariumsolani, Fusarium oxysporum vasinfectum. Test result shows that the inhibition rate of parentcompound6a to the six testing strains are35.97%,15.15%,27.89%,12.59%,41.99%. Itacted out a certain inhibitory activity but the rate is not high. The inhibition rate of targetcompounds7a,7g,7q and7s to the Curvularia lunata is53.2%; The inhibition rate of target compounds7k and7u to the Fusarium oxysporum vasinfectum is59.04%and69.79%.Other target compounds did not acted out a good inhibitory activity to the testingstrains. Structure-activity relationship analysis result shows that, meta-substituentcontaining pyrazole hydrazone compounds show greater inhibiting effect to pathogen fungisthan ortho and para substituents containing compounds. Derivatives containelectron-withdrawing groups can better promote the inhibitory effect to the Curvularialunata. Derivatives contain electron-donating groups can better promote the inhibitory effectto the Fusarium oxysporum vasinfectum.