Synthesis, Characterization And Biological Activity Of Novel Pyrazole-bipyrrole Compounds

As the new representative heterocyclic fungicide,ludioxonil is product with high efficiency,low toxicity,long persistence and good tolerance.the main active group of which is the fluorine atom substituted on the phenyl ring and cyano pyrrole.In order to find new potential fungicide candidates with higher biological activity and environmentally friendly properties,we designed and synthesized eleven new pyrrolpyrazole compounds based on the structures of ludioxonil.The original benzene ring in fludioxonil structure is replaced by the pyrazole ring to improve its bactericidal activity.The target molecules are synthesized by cyclization,formylation,substitution,condensation and cyclization reactions with ethyl acetoacetate and methyl hydrazine as starting materials.The products from this reaction route are with good purity and high yield and the reaction conditions are mild for control,which is suitable for large scale production.The paper also investigated the effect of different reaction factors such as the solvent,the reaction temperature,reaction time,material ratio and catalyst etc.,on the reactions to obtain the optimal reaction conditions.The analysis methods by HPLC of the target products and intermediates are also established.And six single crystals of final products are also been achieved by volatilization under room temperature.All the structures of target products and their intermediates are characterized and confirmed by IH NMR,FTIR,single crystal diffraction,HPLC and melting point determination.Seven of this series of compounds were tested for biological activities.The results show that each of the compounds exhibit certain antibacterial activity toward rhizoctonia,botrytis cinerea and cucumber downy mildew,which provides valuable information for further development of new pesticides fungicides.