Photoinductive Ni-catalyzed C-N/C-O Coupling And Its Application In Pesticide Synthesis

Many drugs,fine chemicals,and natural products contain aryl amines or aryl ester structures,so there is great value in converting cheap and commercially available aryl halides into aryl amines or aryl esters.Transition metal catalytic coupling of aryl halides with amines or acids to aryl amines or aryl esters has made great progress recently.Moreover,the recent developments in photocatalysis have made the reaction conditions more green and environmentally friendly.However,traditional photocatalytic reactions require the addition of photosensitizers such as iridium or ruthenium as the bridge between light and reaction,which is costly.Recently,progress has been made in the study of direct light-excited nickel organic complexes,which inspire us to establish a visible light-induced nickel catalytic system to achieve the cross coupling of aryl halides and amines or acids efficiently.This article is divided into five chapters:the first part describes the aromatic amine and aryl esters pesticide molecules and light catalytic organic machanism,and from the perspective of synthesis,simple overview on the industrial synthesis of aromatic amine and pesticides in recent years,the light and the catalytic organic reactions of transition metal collaborative strategy,focuses on photocatalytic auxiliary cheap transition metal Ni catalyzed coupling reaction model.In chapter two,we successfully achieved the cross coupling of aryl iodide and amine by photoinduction,using cheap Ni Br₂·glyme as catalyst and 4,4’-di（tert-butyl）-2,2’-bipyridine（dtbpy）as ligand.Although the photocatalytic reactions reported by predecessors can be compatible with all kinds of amine and aryl halides,they need to add photosensitizer,which makes the reaction cost higher and the reaction system more complex.Our reaction does not require the addition of additional photosensitizer,achieving efficient and low-cost construction of C-N bond.The reaction yield of the optimized model was up to 96%.Using this condition,we extended 16 amine compounds and 10 aryl halide compounds,which can be compatible with alkyl primary amines,alkyl secondary amines,aryl amines,amides and sulfamides.Various aryl iodides are also suitable for this system,and the yield of electron-deficient and electron-rich aryl iodides and heterocyclic iodides are high.It is found that the effect of 420 nm light is better than 390 nm light commonly used in the previous photoinduced nickel catalysis.Then the mechanism of the reaction is preliminarily studied.According to the previous research experience,we guess that there are two possible mechanism pathways in our experiment.The first reaction mechanism is the stable Ni（II）organic complex produced by excitation of light.For this purpose,we first synthesize stable intermediate Ni（II）aryl iodine complex,and then make it and amine react to form Ni（II）aryl amine complex in solution.However,it was found that the target product yield under light condition was similar to that under dark condition,a little.Therefore,light excitation of Ni（II）organic complex is not feasible.The second mechanism may be the occurrence of ligand metal single electron transfer（LMCT）pathway to generate active Ni（I）,it may catalytic reaction.We successfully captured tetrahydrofuran radical with stilbene.Thisradical maybe generated by the reaction of tetrahydrofuran and free radical generated in the LMCT process.So the overall reaction mechanism is a Ni（I）/Ni（III）cycle.In the end we successfully synthesized three commercial pesticides--mecholone,flucolone and dicolone with the NMR yields of 52%,57%and 50%,respectively,which confirmed the practicability of the reaction system.In general,dangerous phosgene is used to synthesize amide pesticides in industry,and the process is complicated.However,we use N,N-dimethylurea and aryl iodine in one step to synthesize amide pesticides,which has obvious advantages.The third chapter studies the esterification reaction between aryl halides and acids.The reactions reported by predecessors also need to add photosensitizer.We followed the reaction system in Chapter two,gaining good result,but different wavelengths of light may be required when different substrates are used,so we optimized the light with different wavelengths.When 450 nm light was used,the yield of the model reaction was up to 90%.The system is compatible with various primary,secondary,tertiary,aryl and heterocyclic acids.For aryl halides,it can be compatible with various aryl iodides,electron-deficient aryl bromides and heterocyclic bromides.The results provide a new and effective strategy for the esterification of aryl halides.In the fifth chapter,we successfully synthesized three commercial pesticides--mecholone,flucolone and dicolone with the NMR yields of 52%,57%and 50%,respectively,without using photosensitizer,which confirmed the practicability of the reaction system.In general,dangerous phosgene is used to synthesize amide pesticides in industry,and the process is complicated.However,we use N,N-dimethylurea and aryl iodine in one step to synthesize amide pesticides,which has obvious advantages.