Visible-light Induced And Thermally Initiated Arylation

Aromatic rings are widely found in natural products,drug molecules,functional materials,etc.As a result,it is of great significance for drug research and material modification to develop efficient arylation methodologies.Among them,transition metal-catalyzed coupling reactions have been extensively studied by chemists and a series of excellent results have been obtained.These reactions usually involve the intermediates formed by the oxidation addition of transition metals to aryl precursors.In addition,aryl radicals and aryl cations are also effective intermediates for arylation.In recent years,the aryl migration strategy as an effective means of aromatization modification to a fragment of a molecule,has obtained great development and application.The research in this thesis mainly focuses on the development of aryl radical precursors and the application of arylation reaction,meanwhile the development of arylation methodology in accordance with green chemistry.Furthermore,based on the concept of green chemistry,trifluoromethylation of enamides without transition metal was realized at room temperature.The first part of the thesis focuses on the development and application of aryl radical precursors.We found that benzotriazinone derivatives can work as precursors of aryl radical.A visible-light-promoted regioselective denitrogenative insertion of terminal alkynes into 1,2,3-benzotriazinones is realized.This method can be widely used in the synthesis of polysubstituted isoquinolones.Finally,the aryl radical was successfully captured by a reasonable experimental design.The second part of the thesis focuses on the research of aryl cations.Quinoline derivatives were obtained from diazonium salts,alkynes and nitriles in high selectivity under heating conditions.The reaction conditions are mild,no additive is needed,nitrogen protection is not necessary,and the operation is simple.In addition,the substrates have good applicability,and different polysubstituted quinoline compounds can be obtained in good yield.The third part of the thesis focuses on the functionalization of olefins by using aryl migration.We use the new version of Umemoto's reagents as trifluoromethyl radical precursor,which can produce trifluoromethyl radical only under visible light irradiation,and then trifluoromethyl radical react with olefin to realize aryltrifluoromethylation of olefins.The reaction is green and environmentally friendly without transition metal participation and can progress at room temperature.The substrate has good applicability and high tolerance of functional groups.Meanwhile,excellent chemical selectivity and regional selectivity are observed.The fourth part of the thesis focuses on the remote aryl migration of amides.The relationships among the aryl migration,HAS(homolytic aromatic substitution)and HAT(hydrogen atom transfer)in distal aryl migration of amide with NIS as oxidant are discussed.We found that in most cases aryl migration is dominant;HAS and HAT can be well inhibited.However,when there exist the reaction sites containing tertiary carbon or benzyl sites which are suitable for HAT,HAT has a competitive relationship with aryl migration.Finally,we synthesized the 8-member cyclic sulfonamide atropisomers by using the aryl migration strategy of amide.Furthermore,it was found that the rigidity of molecules also had an effect on the selectivityThe fifth part of the thesis focuses on trifluoromethylation of enamides.We take advantage of the experimental phenomenon that the Umemoto can directly split into trifluoromethyl radical just under visible light to realize the trifluoromethylation of enamides without transition metal participation.Substrates have good applicability and the reaction accords with the idea of green chemistry.