Application Of Visible Light Promoted Fe Catalyzed Decarboxylation In The Construction Of Carbon Carbon And Carbon Nitrogen Single Bond

In recent years,in the field of organic photochemistry,rhodium,iridium and other complexes have played a remarkable role,but the content of iridium and ruthenium in the crust is quite small,so the price of iridium and ruthenium complexes has been very expensive,which restricts the development of photochemistry.Iron is the second most abundant metal element on earth,and a lot of pioneering work in the field of photochemistry and photophysics(before 1970)is based on its complexes.However,the photoexcited state lifetime of iron complexes is usually much shorter than that of iridium and ruthenium complexes,which makes the application of iron complexes in photochemical organic synthesis a considerable challenge.Therefore,it is of great significance to develop abundant and cheap metal iron complexes to replace ruthenium,iridium and other precious metal complexes in photochemistry.In view of this,the Fe mediated photocatalytic decarboxylation was designed and realized.Through the strategy of decarboxylation of carboxylic acid induced by iron complexes and ligands,under visible light,carboxylic acid decarboxylates under the control of ferric sulfate and ligands.The resulting alkyl radicals react with appropriate electron deficient double bond receptors(carbon carbon,nitrogen nitrogen double bond)to construct the corresponding carbon carbon and carbon nitrogen single bond.First of all,through the selection of solvent,light source,iron salt and ligand,we finally determined the optimized reaction conditions: the amount of carboxylic acid is twice that of olefin / carboxylic acid is four times that of azo carboxylic acid ester,2.5 mol% iron sulfate,5 mol% dimethylpyridinamine as the ligand regulation,the reaction solvent is Dichloroethane(DCE),and the light source is 427 nm for 12 h.Under these conditions,we successfully used iron photocatalysis to realize a mild and effective method for the formation of decarboxylation C-C and C-N bonds.Then,under the optimal conditions,we examined the substrate application range of the reaction,and finally obtained a series of the addition products of carbon carbon single bond and carbon nitrogen single bond.Finally,we also studied the possible mechanism of the reaction.In this paper,the addition products of carbon carbon single bond and carbon nitrogen single bond were characterized by a series of methods(NMR,HRMS,IR),and the accurate structures of all products were determined.This method provides a new way for iron photocatalytic decarboxylation and alkylation of carboxylic acids,and it is also a supplement to Michael addition reaction in the application of carbon carbon and carbon nitrogen single bond construction under the visible light conditions.