Synthesis And Antifungal Activities Of Thiadiazone Or Thiazole Derivatives Bearing Pyridine Ring

Heterocyclic pesticides has become an increasingly important role in pesticides due to their specific selectivity,higher biological activity,lower toxicity to human body and stronger pertinence for physiological activity.A lot of heterocyclics,such as pyrrole,pyrimidine,pyridine,thiazole,thiadiazole,benzimidazole,have shown favourable biological activities and many of them have come into commercialization.In addition,amides with the characteristics of wide sterilization spectrum,novel structure,flexible designing,have good potentials in pesticide synthesis.In order to find the compounds with higher antifungal activity and better specificity,we introduced thiadiazole and benzoylamino moieties,or thiazole and benzylidene moieties to the pyridine ring based on the active binding principle.Two series of pyridine compounds have been synthesized and evaluated for their antifungal activity against two plant pathogens?S.sclerotiorum and B.cinerea?by the growth rate of mycelium method.The research conclusions have been shown in the following.1.Based on pyridine,a series of novel 5-?substituted benzylidene?thiazolidin-4-ones???containing 3-pyridinlyimino moiety were synthesized by acylation,cyclization and Knoevenagel condensation reactions;another series of novel N-[5-?3-pyridylmethyl?-1,3,4-thiadiazol-2-yl]benzamide???containing 2-chloro-N-?pyridin-3-yl?acetamide moiety were synthesized by cyclization and amidation.2.All the novel compounds were characterized by¹H NMR,¹³C NMR,IR spectra and elemental analysis?or HRMS?.In series ?,the yield was improved by changing the solventand acid-binding agent.In series ?,the temperature of the reaction conditions are explored in detail,and optimized temperature is 85? at last.3.The antifungal activities of the target compounds were evaluated against S.sclerotiorum and B.cinerea in vitro.The results indicated that some of the compounds had certain inhibitory activity on the two fungi.Compound Ib has shown moderate antifungal activity against B.Cinerea with inhibitory rates of 71.2% at 50 ?g/mL,and 78.4% at 100 ?g/mL.Compound Ia has shown high antifungal activity against B.Cinerea with inhibitory rates of79.0% in 100 ?g/mL;Compound ?c exhibited good antifungal activity against B.Cinerea with inhibitory rate of 78.8% in 100 ?g/mL.The structure activity relationship indicated that the target compounds bearing 2-Cl substituent had shown good antifungal activity;the compounds bearing electron-withdrawing groups exhibited better antifungal activity compared with ones bearing electron-donating groups.In general,antifungal activities of thiazole derivatives are better than those of the thiadiazole.