Design,synthesis,and Herbicidal Activity Of 4-Hydroxyaurones And N-acylsulfonamides

The development of new,efficient,and environment-friendly herbicides is an inevitable trend with the development of society and environmental awareness,which not only ensures the healthy and sustainable development of modern agricultural production,but also provides basis for ecological security,food security and agricultural trade security.Natural products possess the advantages of high selectivity,easy degradation,less pollution to the environment,and producing resistance slowly,which make them have the possibility to be the lead compounds in the development of new pesticides.Aurone is a kind of natural products which has good herbicidal activity against dicotyledons plants Brassica campestris L.（B.campestris）.Our group has carried out a preliminary study on the structure optimization and herbicidal activity of aurones.On the basis of our previous studies,35 4-hydroxyaurones and their derivatives were designed and synthesized in this paper.Based on their structural characterization,their herbicidal activity and structure-activity relationship were studied.In addition,16N-acyl sulfonamides were designed and synthesized,and their herbicidal activities were evaluated.The specific content is as follows:Ⅰ.Synthesis and herbicidal activity of 4-hydroxyaurones（TM-1～TM-35）1.22 4-hydroxyaurones（TM-1～TM-22）were synthesized by the aldehyde condensation reaction with aromatic aldehydes after a hydroxyl protection,α-bromination,hydrolysis and cyclation by using 2,6-dihydroxy acetophenone as raw material.All the target compounds were characterized by ¹H NMR,¹³C NMR and elemental analysis.The bioassay revealed that 4-hydroxyaurones exhibited moderate to good herbicidal activities against dicotyledons plants B.campestris and Amaranthus retroflexus L.（A.retroflexus）for post-emergence treatment at a dosage of50 g/mu.For example,the herbicidal activity of compound TM-13 against A.retroflexus was 74.5%,which was significantly higher than that of acetachlor（55.8%）.The preliminary structure-activity relationship indicated that the introduce of hydroxyl group into the 4-position of aurones was beneficial to herbicidal activity,which was worth proceeding further structural optimization.2.Totally 13 4-methoxyaurones and 4-acyloxyaurones（TM-23～TM-35）were synthesized,and their herbicidal activity was studied by greenhouse test（50,25,12.5g/mu）after their structural characterization by ¹H NMR,¹³C NMR and elemental analysis.The results showed that the the target compounds showed high herbicidal activities against B.campestris and A.retroflexus for post-emergence treatment.When the dosage of the compounds was reduced to 12.5 g/mu,the herbicidal activities of TM-32 and TM-35 against B.campestris were still up to 85.3%and 81.6%,which were slightly lower than that of mesotrione（90.2%）,and significantly higher than that of acetochlor（0%）.In addition,we also discussed the structure-activity relationship of4-hydroxyaurones,which provided a basis for further structure optimization.Ⅱ.Synthesis and herbicidal activity of N-acyl sulfonamides16 N-acyl sulfonamides（TM-36～TM-51）were synthesized from（un）substituted phenylacetic acid and p-sulfonamide benzoic acid,and their structures were confirmed by ¹H NMR,¹³C NMR and elemental analysis.The rape cup test and barnyardgrass cup test results showed that most of the N-acylsulfonamides had good inhibitory effect on the root length of rape,but weak inhibitory effect on the plant height of barnyard grass at the dosage of 100μg/m L and 10μg/m L.For example,TM-43 showed 96.5%and 88.4%inhibitory activities against root length of rape at100 and 10μg/m L,respectively.The structure-activity relationship showed that the electrical property and location of the R₁ group in the target compounds had significant effects on herbicidal activity.These results provide a foundation for further design of high herbicidal activity compounds.