Synthesis And Antifungal Activity Of 2-styrybenzimidazoles

Benzimidazole is a very important heterocyclic compound in the field of drug design and synthesis.In the past few decades,the study of benzimidazole has received considerable attention.As the problem of drug resistance is becoming more and more serious,new benzimidazole drugs are urgently needed to be developed.Based on the previous research on cinnamate in this topic,the combination of cinnamic acid and benzimidazole was used to design and synthesize 2-styrybenzimidazole and its derivatives,and its anti-phytopathogens were systematically investigated.The activity of the fungus was analyzed and its structure-activity relationship was analyzed.The research results obtained in this experiment are as follows:（1）Compounds 1-20 and 33 are synthesized by substituting cinnamic acid or butyric acid and substituted o-phenylenediamine;compound 21-28 is synthesized by（N-）alkylation reaction of imidazole ring（B ring）;Compounds 31 and 32 were synthesized from cenoic acid and o-phenylenediamine;amide compounds 29 and 30 having the same structural length and similar structure to the template carbon chain were designed and synthesized.There are28 known compounds and 5 new compounds.All compounds were characterized by nuclear magnetics.（2）At 50 mg/L,the antibacterial activity of 33 compounds against 6 plant pathogenic fungi（potato rot,pumpkin wilting,apple anthrax,rice blast,watermelon wilting and tobacco red star）was determined.The results showed that all the compounds except compounds 31and 32 had different degrees of inhibition on the six strains.Compared with the positive drug thiabendazole,some drugs were found to be better than the positive drugs.Through the virulence activity test,the EC₅₀ of rice blast and tobacco red star was better than that of thiabendazole for the wilting of pumpkin.For potato dry rot and apple anthrax,compounds 7and 29 were found to be superior to thiabendazole,and the EC₅₀ was 2.06.mg/L and 1.76mg/L.（3）Analysis of structure-activity relationship:Through analysis of structure and activity,it was found that the substituents on the C ring and their substitution positions can significantly affect the activity.Substituents on the A ring can also significantly affect activity,and the effects of substituents on the A and C rings on the activity are interdependent.The（N-）alkylation of the imidazole ring（B ring）does not significantly enhance the activity,and the degree of influence varies with the hydrocarbon group.The presence of a carbon-carbon double bond between the B ring and the C ring and the aromatic ring C is necessary for high activity.The 2-amido group significantly enhances the activity of the compound against individual bacteria compared to the 2-styryl group.The results of the indicate that 2-styrybenzimidazoles have the potential to be developed into novel antimicrobial agents.The research results have guiding and reference value for the follow-up research work of such compounds.