Efficient Stereoselective Synthesis Of Chiral Pesticide Active Nitrogen Heterocyclic Molecules And Study Of Their Biological Activitie

Chiral pesticides are chemical products widely used for Disease Control in agriculture and industry.In the chiral environment,usually one enantiomer of chiral pesticides has activity to the target organism,while the other enantiomers have no activity.Moreover,the enantiomers of chiral pesticides are usually metabolized at different rates,and the inactive enantiomers will be discharged into the environment,causing toxicity to non-target organisms.Therefore,the high-efficiency stereoselective synthesis of chiral pesticides is an important means to develop new high-efficiency and low toxicity green pesticides.N-Heterocyclic Carbene（NHC）used as a new and mild catalyst,has a variety of activation modes and rich reaction forms.Therefore,it can be used to efficiently construct of axially chiral and polychiral central compounds in combination with the current research hotspots in the pesticide industry,and their biological activities were preliminarily explored.Firstly,the acylthiourea and phenylpropargyl aldehyde substrates were used to synthesize the axially chiral thiazine compounds under the catalysis of NHC.The reaction has a broad substrate scope and excellent stereoselectivity.Subsequently,the sensitivity of the model reaction to external conditions（temperature,moisture,air,etc.）was studied.The stereochemical stability of the target compounds was explored according to theoretical calculations and relevant experiments,and the possible reaction mechanism was proposed.A series of axially chiral thiazine compounds were synthesized by this method,and the application of corresponding target products were explored.By adjusting the configuration of the catalyst,the rac,R,S-configurations of the corresponding products were synthesized.Secondly,chromeno[4,3-b]pyrrole derivatives with multiple chiral centers were efficiently constructed in one step according to the NHC-catalyzed cascade reaction.The structures of the target compounds were characterized by ¹H NMR,¹³C NMR and HRMS.Then the absolute configuration was determined by X-ray single crystal diffraction analysis.The reaction has a broad substrate scope,and the reaction mechanism was studied by the deuterization of different substrates.Finally,the Rac,R,S-configurations of axially chiral thiazine compounds and multiple chiral complex compounds were synthesized by using the above established method.Its biological activities were also studied.The antibacterial biological activity of thiazine compounds was determined by turbidimetry test,and the effects of axially chiral compounds with different configurations on their biological activity were studied.A highly active compound（R）-3-3q was found through preliminary screening of biological activity,and its curative and protective activities were explored through in vivo pot experiments.It was found that its control effect on rice bacterial blight was better than that of commercial drug thiodiazole copper;At the same time,the bioactivities of chromeno[4,3-b]pyrrole compounds with different configurations were evaluated by the growth rate method.The test objects were Phytophthora capsici and Colletotrichum fructicola isolated from the field.The test results showed that the bioactivities of these compounds were moderate,but the configuration had a great impact on the bioactivities.