Radical Coupling Reactions And Povarov Reactions Via Cooperative Photoredox And Asymmetric H-bonding Catalysis

In recent years,with the development of chemical technology,chemists have been working hard for the reaction conditions of simplicity,moderation and low environmental pollution.Sunlight is a green energy with abundant reserves and no pollution.The rational application of solar energy into production has led to many subjects such as biophotochemistry,photoelectrochemistry,and photocatalysis.Among them,photocatalysis converts light into chemical energy in order to drive electron transfer in the chemical reaction process to form active free radicals,which are used in chemical synthesis.Moreover,photocatalysis can overcome several harsh reaction conditions of conventional methods,as well as the problem of functional group limitations,and realize the efficient synthesis of compounds.?²-and?^2,2-amino ketones and heterospin compounds?including isoindolinone or 1,2,3,4-Tetrahydroisoquinoline ring?are the basic parts in some natural products.Based on the previous research of photocatalysis and asymmetric catalysis,we use the dinitrazine derivatives DPZ as a organic photocatalyst and Bronsted acid as a chiral catalyst to synthesize chiral?²-and?^2,2-amino ketones and spiro compounds.1.Free radical coupling reaction of alkyl halides via cooperative photoredox and asymmetric H-bonding catalysisClassic nucleophilic substitution reactions?S_N1 and S_N2?are not generally amenable to the enantioselective variants that use simple and racemic alkyl halide electrophiles.The merging of transition metal catalysis and radical chemistry with organometallic nucleophiles is a versatile method for addressing this limitation.Here,we report that visible light-driven catalytic asymmetric photoredox radical coupling can act as a complementary and generic strategy for the enantioconvergent formal substitution of alkyl haldies with readily available and bench-stable organic molecules.Single-electron reductive debrominations of racemic?-bromoketones generate achiral alkyl radicals that can participate in asymmetric Csp3–Csp3 bonds forming cross-coupling reactions with?-amino radicals derived from N-aryl amino acids.A wide range of valuable enantiomerically pure?²-and?^2,2-amino ketones were obtained in satisfactory yields with good-to-excellent enantioselectivities by using chiralphosphoric acid catalysts to control the stereochemistry and chemoselectivity.Fluoro-heteroquaternary and full-carbon quaternary stereocenters that are challenging to prepare weresuccessfully constructed.2.Povarov reaction of 3-methylene isoindolinones via cooperative photoredox and asymmetric H-bonding catalysisHeterospiro compounds are widely used in organic chemistry,pharmaceutical chemistry,material chemistry and so on.Recently,the design and synthesis of different types of spiro compounds are increasing.There are many steps to synthesize heterospiro compounds,together with the low yield.Therefore,it is of great significance to develop some new and simple synthetic routes for the synthesis of heterospiro compounds in high yield.At the same time,the isoindolinones and quinoline ring compounds are the basic parts of the potential biological activities of some natural products.Under the air and light conditions,using DPZ as photocatalyst,N-arylglycine is oxidized twice to N-aryl imine.By using the chiral Bronsted acid as a chiral catalyst,the povarov reaction between the 3-ylidene isoindolinone and the N-aryl imine generates products which containing 1,2,3.4-tetra-hydroquinolinering or isoindolinone ring with high stereoselectivities and good yields.