Study On The Oxidative[3+2]Cycloaddition Reaction Of Phenols And Olefins

The dihydrobenzofuran cores exist in many bioactive natural products.Therefore the construction of dihydrobenzofuran core has attracted broad attention from organic chemists.The oxidative[3+2]cycloaddition of phenols and olefins serves as a concise strategy for construction of dihydrobenzofurans.Heterogeneous photocatalysis meets the requirements of green chemistry and has been applied in degradation of organic pollution and organic transformation.In this thesis,the heterogeneous photocatalytic oxidative[3+2]cycloaddition of phenols and olefins is designed.Hopefully,this work can provide an environmentally friendly strategy for constructing the dihydrobenzofuran cores.The first chapter mainly introduces the progress of oxidative[3+2]cycloaddition of phenols and olefins.The second chapter describes the present application of heterogeneous photocatalysis in the field of organic synthesis.In the third chapter,Au/TiO25 Au/Al2O3,Au/CeO2,Au/ZrO2 and Au-Pd/TiO2 photocatalysts were prepared and characterized.Then these heterogeneous photocatalysts was used in the study on the oxidative[3+2]cycloaddition of phenols and olefins,unexpectedly the results show this reaction was achieved by using 2,3-dichloro-5,6-dicyanobenzoquinone(DDQ)as oxidant and 1,1,1,3,3,3-hexafluoropropan-2-ol(HFIP)as solvent at room temperature in the absence of catalyst and light.With this method,a broad range of dihydrobenzofurans were efficiently and quickly obtained from readily available phenols and alkenes.In the fourth chapter,firstly semiconductor photocatalyst BiVO4 was prepared and characterized.Then the BiVO4-catalyzed oxidative[3+2]cycloaddition of phenols and olefins was explored.The results demonstrated that this reaction was accomplished by using HFIP as solvent,30%H2O2 as an oxidant,BiVO4 as catalyst.This work provides a new heterogeneous catalytic method for green synthesis of dihydrobenzofurans.The fifth chapter introduces the experimental procedure and characterization of products.In summary,two concise and efficient methods for construction of dihydrobenzofurans were established in this thesis,which pave the way for further research of the heterogeneous photocatalysis in organic sysnthesis.