Design And Synthesis Of Highly Selective And Ecologically Safe Herbicides Based On Allelochemicals

Because of diverse biological activities,unique modes of action,and environmental friendliness,allelochemicals have become one of the ideal lead compounds for the development of green pesticides.Tricin（5,7,4’-trihydroxy-3’,5’-dimethoxyflavone）is an allelochemical isolated from rice and inhibits the growth of rice sedge,sedge and broken sedge.Related studies have shown that flavonoid-derived aurone derivatives have higher herbicidal activity and selectivity for dicots.,Isoflavone and chalcone are also isomers of flavonoids structurally,which have been extensively studied in the medical field,but there are few studies on agricultural use.Therefore,in order to study the application potential of isoflavone and chalcone in weed control,the aryloxyacetoxy groups in aryloxycarboxylic acid herbicides were introduced into isoflavone and chalcone structures by active substructure splicing.Finally,64 target compounds were designed and synthesized.Herbicidal activity and and crop safety research was tested based on the ¹H NMR,¹³C NMR and elemental analysis,The specific contents are as follows:1.Synthesis and herbicidal activity of 7-Aryloxyacetoxyisoisflavone derivativesThe deoxybenzoin was prepared by using resorcinol and substituted phenylacetic acid as raw materials,and then reacted with a cyclization reagent to prepare 11 key intermediates–7-hydroxyisoflavone derivatives（I-1^I-11）.Then compounds（I-1^I-11）and different aryloxyacetyl chlorides（D1^D4）made a nucleophilic substitution reaction to get 29 novel 7-aryloxyacetoxyisoflavone derivatives（TM-1^TM-29）.The structures of target products were confirmed by ¹H NMR,¹³C NMR and elemental analysis.The results of the rapeseed plate test showed that some target compounds showed good herbicidal activity comparable to 2,4-D and significantly higher than 77%2,4-D isooctyl ester.The compounds also exhibited a certain structure-activity relationship:the electrical properties and positions of the R¹ and R² groups had important influence on the herbicidal activity of the compounds.Further greenhouse pot experiment（50,25,12.5 and 6.25 g/mu）showed that the target compounds showed good herbicidal activity against dicotyledonous plants（canola and leek）,and the efficacy of stem and leaf treatment of dicotyledons was generally higher than that of soil treatment,and remained unchanged with 2,4-D.TM-3^TM-5 herbicidal spectrum showed that TM-4 and TM-5 can effectively control common broadleaf and other broad-leaved hybrids such as purslane and alfalfa in the dose range of 12.5²5 g/mu.TM-4 inhibited the fresh weight of Alkali reaching 28.1%under 25 g/mu,showing a broader herbicidal spectrum than 2,4-D.Crop safety results indicated that TM-3^TM-5 was safe for wheat at a dose of 12.5 to 25 g/mu after seedling.In addition,TM-4 was safe for corn and cotton in this range,and it had improved the safety of cotton and wheat than 2,4-D,and has the possibility of developing new varieties of herbicides.2.Synthesis and herbicidal activity of aryloxyacetoxychalcone derivatives16 intermediates-chalcone derivatives（I-12^I-27）were synthesized by substituted benzaldehyde and hydroxyacetophenone under the base catalysis.Different aryloxyacetyl chlorides（D1^D4）and intermediates（I-12^I-27）made a nucleophilic substitution reaction to get 35 aryloxyacetoxychalcone derivatives（TM-30^TM-64）.The structures of all target compounds were confirmed by ¹H NMR,¹³C NMR and elemental analysis.The results of rapeseed test showed that target compounds had different inhibitory effects on the root length of dicotyledonous rape.Some compounds inhibited 2,4-D rapeseed and showed a certain structure-activity relationship.Further greenhouse potting results showed that the compounds TM-30,TM-31,TM-41 and TM-60 had excellent control effects on dicots（canola and leeks）at 25 g/mu,and the stem and leaf treatment effects were excellent.For soil treatment;some compounds had certain control effects on monocotyledons（herbs and horses）,and soil treatment was better.