Synthesis Of Benzoxazoles And Benzothiazoles And Research Of Their Antifungal Activity

Benzoxazoles and benzothiazoles are very important kinds of nitrogen containingheterocyclic compounds, which usually act as the important guide frame and maternalskeleton, Their derivatives often have high biological activity, thus they play very importantroles in in pesticide, pharmaceutical and industrial fields. In pesticide fields, benzoxazoles andbenzothiazoles often have good selectivity, high activity, green environmental protectionadvantages，so they have become research topics and research focus in pesticide researchtoday; In the field of medicine, benzoxazoles and benzothiazoles have anti-inflammatory,anti-cancer, anti-cancer and other activities so they can be made into novel medicament; Inthe industry, they can be used as colorants, preservatives, dyes, rubber vulcanizationaccelerator and luminescent materials.In this paper, o-aminophenol,2-aminobenzenethiol are used as raw materials to synthesis2-chloromethyl benzoxazole and2-chloromethyl benzothiazole,which act as twointermediates, and then they are used as the maternal skeleton to synthesis29benzoxazolesand benzothiazoles through the etherification reaction,¹HNMR,¹³C NMR, IR, MSspectroscopy methods are used to determine the chemical structure of these compounds,15ofwhich are new compounds.The invitro growth inhibition assay of these compounds against phytopathogenic fungiare carried out with mycelial growth inhibitory rate method. The result indicated that:（1）LB-9has wide ranges of biological activity on all of these eight species ofphytopathogenic fungi.（2）LB-2has significantly stronger activity towards Fusarium sulphureum (IC₅₀=0.03±0.32μg/mL) than positive control compound hymexazol (IC₅₀=22.18±1.96μg/mL), It alsohas equal activity to Colletotrichum gloeosporiides (IC₅₀=83.35±1.61μg/mL) andValsamali(IC₅₀=37.98±0.86μg/mL) with the positive control compoundhymexazol(IC₅₀=156.08±1.38μg/mL and159.49±0.78μg/mL respectively).（3） LB-27has significantly stronger activity towards Alternaria solani (IC₅₀=32.10±0.97μg/mL), Fusarium sulphureum(IC₅₀=8.48±1.29μg/mL) Colletotrichumgloeosporioides(IC₅₀=32.78±1.32μg/mL), compared with the positive control compound hymexazol(IC₅₀=96.72±1.00μg/mL,22.18±1.96μg/mL and156.08±1.38μg/mLrespectively).From compounds with antifungal activity results, We can come to conclusion of thestructure-activity relationships as follows:（1）The introduction of F, Cl atoms into2-substituted benzene of benzoxazoles andbenzothiazoles can significantly enhance the activity;（2）In2-substituted acetophenones of benzoxazoles, the meta position of phenyl ring havethe best activity, the ortho position and para position are followed.（3） On the whole, the benzoxazole compounds to phytopathogenic fungi activity wassignificantly stronger than the same types of benzothiazole compounds.In summary, benzoxazoles and benzothiazoles synthesis and antifungal activity arestudied in this paper, which can provide academic basis for the research of new types ofpesticide.