Synthesis And Insecticidal Activity Of ?-dihydroagarofuran Sesquiterpenoids Derivatives

1?,2?,4?,6?,8?,9?,12-hepthydroxyl-?-dihydroagarofuran was used as starting material,which has been isolated from the hydrolysate extract of the root bark of Celastrus angulatus Max.Many ?-dihydroagarofuran derivatives were designed to synthesize,and their insecticidal activities were evaluated with sixth-instar larvae of Mythimma separata by the ether anaesthetized and forced-feeding method.The main results are as follows.1.Synthesis and structure characterization(1)The lead compound 2 was synthesized by the main material 1?,2?,4?,6?,8?,9?,12-hepthydroxyl-?-dihydroagarofuran.Compound 2 was protected with polyoxymethylene,aldehyde,propanal,butyraldehyde,isobutyraldehyde to produce compound 2.1-2.5.55 target compounds 2.1.1-2.1.11,2.2.1-2.2.11,2.3.1-2.3.11,2.4.1-2.4.11,2.5.1-2.5.11 were synthesized by the reaction of 2.1-2.5 with sodium hydride and subsequent treatment with corresponding haloalkanes.(2)Compound 2 was protected with acetone under the catalysis of ferric chloride to produce ketal compound 2.6.Then compounds 2.6.1-2.6.9 were synthesized by the reaction of 2.6 with sodium hydride and subsequent treatment with corresponding haloalkanes.After that compounds 2.6.1.0-2.6.9.0 were synthesiezed by the acetone removed reaction of 2.6.1-2.6.9 under catalysis of 0.8% sulfonic acid.Finally,18 target compounds 2.6.1.1-2.6.9.1?2.6.1.2-2.6.9.2 were synthesized by the reaction of 2.2-2.5 with sodium hydride and subsequent treatment with o-fluorobenzyl bromide,and p-fluorobenzyl bromide.(3)All target compounds were mainly characterized by 1H NMR?13C NMR and DEPT-135°,in addition,the configuration of compound 2.3.7 was confirmed by the NOESY spectroscopy,and the configuration of compound 2.5.11 was confirmed by the X-ray crystal diffraction.2.Insecticidal activity assay Sixth-instar larvae of Mythimna separata was used to test the insecticidal activity of the 73 ?-dihydroagarofuran derivatives with the method ether anaesthetized and forced-feeding,and the results indicated that compounds 2.1.4?2.1.7?2.1.8?2.1.10?2.1.11?2.2.4?2.2.9?2.2.10?2.2.11?2.3.2? 2.3.4?2.3.5?2.3.6?2.3.7?2.3.8?2.3.9?2.3.10?2.3.11?2.4.2?2.4.3?2.4.6?2.4.10?2.5.3?2.5.4?2.5.7 exhibited excellent insecticidal at a concentration of 20 mg/mL and dosage of 1?L.The results of LD50 determination revealed that the LD50 values of compounds 2.1.10?2.2.9?2.2.10?2.2.11?2.3.4?2.3.6?2.3.7?2.5.4?2.5.7 were all lower than that of celangulin-V,especially that of compound 2.2.11(60.33 ?g/g).The structure-activity relationship showed that ethyl,n-propyl,n-butyl,allyl,propargyl,o-fluorobenzyl,and p-fluorobenzyl were active groups.This work could provide important theory and experimental basis for the development of efficient,environmentally friendly pesticides.