Study On Green Synthesis Of Benzoazole,Benzoxazinone And Quinolinone Benzo Nitrogen-containing Heterocycles

Benzo-fused nitrogen-containing heterocyclics such as Benzoazoles,benzoxazinone,and quinolinone are very attractive scaffolds in material science and drug discovery.In recenlt years,ionic liquids?ILs?as green medium have been demonstrated to have unique properties in catalytic chemistry.As catalysts,ILs also showed good activities for many orgainic transformation.On the other hand,visible light mediated chemical transformation is considered a sustainable strategy in organic synthesis.Therefore,in the view of the sustainable chemistry,exploration of new catalysts and development of simple and practical protocols for construction of benzo-fused nitrogen-containing heterocyclics have received great concern.Accordingly,we have developed a reusable thermal activated NHC precursor ionic liquid catalyst for the synthesis of Benzoxazole and benzoxazone.In addition,we also developed external photocatalysts-free visible light induced aerobic transformations of N-alkyl isoquinolinium salts for the synthesis of isoquinolones.The main content of the thesis is as follows:?1?We have designed,synthesized the functional ionic liquid catalyst[BMIm]₂[WO₄].And the structure and physico-chemical properties of catalyst were subsequently characterized.And the oxidative NHC catalysis for synthesis of N-containing heterocyclics by using[BMIm]₂[WO₄]as thermal activated NHC precursor was investigated.[BMIm]₂[WO₄]exhibited the good activity for the base-free condensation and oxidative NHC catalysis tandem under air atmosphere.The catalyst can be recovered and reused for at least five runs in gram scale synthesis without any decrease in catalytic activity.Furthermore,the control experiments demonstrated that the reaction involved formation of aromatic aldimines,NHC-catalyzed oxidative formation of imidoyl azoliums and intramolecular cyclization to generate the product.The carbene activity of[BMIm]₂[WO₄]is due to the proton transfer of the imidazole cation and tungstate anion under higher temperature,which has been demonstrated by temperature-dependent ¹H and ¹³C NMR spectra of[BMIm]₂[WO₄].?2?Based on the synthesis of benzoxazoles,ionic liquid catalyst[BMIm]₂[WO₄]was used to the synthesis of benzoxazinone compounds with anthranilic acid and aromatic aldehyde.This results further confirmed[BMIm]₂[WO₄]as NHC precursor catalyst through imines activation.?3?The aerobic conversion from isoquinoline/quinoline salt to isoquinoline/quinolinone was successfully achieved in the absence of external photocatalysts under visible light irradiation,which provides a highly concise,sustainable and low-cost protocol to unsaturated lactams using air as oxidant.Gram-scale synthesis could be achieved under sunlight and open air condition.Mechanism studies suggested that the generation of singlet oxygen ¹O₂-driven muti-radical process under visible light irradiation plays the important role in the reaction.?4?Using isoquinoline salt as material under visible light irradiation,the yield of N-methylisoquinolinone and 4-iodo N-methylisoquinolinone can be effectively adjusted by different iodine equivalents.On this basis,the synthesis of4-iodoisoquinoline compounds was achieved through condition optimization.