Synthesis And Antifungal Activity Of 3-Carboxylic Coumarin Bishydrazide Compounds

China has a large population,and the Chinese have a great demand for food.The per capita arable land area of China is far below the international average.Therefore,ensuring high food production has always been China’s basic national policy.Plant diseases and pests are the main factors leading to grain reduction.Thus,the rational use of pesticides is an indispensable method for preventing and controlling diseases and pests and ensuring food production.Attribute to the low absorption rate of pesticides,the residual pesticides have caused severe harm to human health and ecological environment.The long-term use of pesticide inevitably triggers the development of pesticide-resistance.As time goes on,pesticide-resistance tends to be serious,and only increase the dosage or replace the variety of pesticide could solve these problems.Increasing the dosage is obviously a stopgap measure.The development of green and efficient pesticide varieties with novel mechanisms of action and unique molecular target has always been an important issue in the fields of agricultural production and plant protection.As an important natural product,coumarin are the secondary metabolites of many plants and have a variety of biological activities.For example,osthol,scopolamine,imperatorin,etc.,have significant antifungal activities.The hydrazide molecule has a unique chemical structure,and its special conjugated system makes it have a wide range of biological activities,which are common active fragments in drug molecules.In this thesis,a series of new 3-carboxylic acid coumarin bishydrazide compounds are designed and synthesized using active substructure splicing and bioelectronic isometric technology.The antifungal activities of these coumarin bishydrazide compounds are determined in order to find lead compound with high antifungal activity.Seven kinds of 3-carboxylic coumarin compounds and a total of 52 bishydrazide coumarin compounds have been synthesized in this paper,of which 45 compounds have not been reported.All target compounds have been subjected to ¹H NMR and ¹³C NMR and high-resolution mass spectrometry（HR-MS）for structural characterization.The growth rate method was used to determine the antifungal activities of target compounds against six common plant disease fungi,Alternaria solani,Alternaria alternata,Botrytis cinerea,Colletotrichum orbiculare,Gibberella zeae and Rhizoctorzia solani.The preliminary screening of the antifungal activity showed that most of the compounds have different levels of inhibitory effects on the six diseased fungi.According to the results of the preliminary screening,the effect concentration value(EC₅₀)of high active compounds were determined.The results showed that compound 2ag possess good inhibitory effects on Alternaria alternata and Colletotrichum orbiculare.Compounds 2bk and 2bq had better inhibitory effects on Rhizoctorzia solani.Compound 2bi can effectively inhibit Colletotrichum orbiculare,and the EC₅₀ value of compound 2bs against Alternaria alternata is 8.67μg/m L,which is equivalent to the control drug Osthole.The experimental results of this thesis provide data support for the further structural optimization research of this kind of coumarin molecules.