Design, Synthesis And Biological Activity Of 1,3,4-oxadiazole (or Thiazole) Hydrazide Derivatives Containing Substituted Benzyl And Phenoxy(thio)methylene Groups

1,3,4-oxadiazole and thiazole compounds exerted the various of biological activities in the field of medicine and pesticide.Based on our previous work and literature research,in this paper,a series of benzyl-,phenoxy(sulfur)-and methylene-substituted 1,3,4-oxadiazole(or thiazole)derivatives containing hydrazide group were designed and synthesized.The structure of target compounds were comfirmed by ¹H NMR,¹³C NMR and HRMS.The antimicrobial activity of target compounds against Gibberella zeae,Fusarium oxysporum,Verticillium dahliae,Thanatephorum cucumeris,Sclerotinia sclerotiorum,Colletotrichun higginsianum,Botryosphaeria dothidea and Phytophora infestins were evalued by mycelia growth inhibition tests.Meanwhile,the antibacterial activities of target compounds against Xoo and Xac were tested by turbidimetric method,while the bismerthiazol and thiodiazole-copper as control drugs.Afterwards,The insecticidal activity of target compounds against Plutella xylostella were determined using a standard leaf?dipping method,while the tebufenozide as the control drug.The results showed that the series A exerted better antimicrobial activity against Phytophora infestins and five plant pathogenic fungi.Notably,most of the compounds showed broad spectrum antifungal activity,which was better activity than the control drugs Hymexazol and Boscalid.Moreover,The EC₅₀ value of compound A₁₈ against Gibberella zeae exhibited the better antimicrobial activity(EC₅₀=0.45 ug/m L)than control drug Carbendazim(EC₅₀=0.95 ug/m L).Compound A₉ showed the best antibacterial activity against the Xoo(EC₅₀=11.4 ug/m L)and Xac(EC₅₀=3.79 ug/m L),which was higher than Bismerthiazol and Thiodiazole-copper.Besides,compound A₁₁ displayed the best insecticidal activity against Plutella xylostella(82%)at the 500?g/m L.Series B compounds showed better antimicrobial activity against 6 plant pathogenic fungi.The activity of most compounds was superior to that of the control drug Hymexazol.Finally,the antifungal mechanism of compound A₁₈ was preliminarily verified.The results showed that compound A₁₈ could deform and break the mycelium of Gibberella zeae,and make the solvend of mycelium leak out,and finally lead to the death of mycelium.