Visible Light Mediated Photocatalytic Catalytic Enantioselective Addition Of Prochiral Radicals To Vinylpyridines

Pyridine is an important azaarene commonly found in pharmaceuticals?agrochemicals?functional materials?ligands and natural products.Moreover,pyridine is not only an important precursor for the synthesis of chiral dihydrogen?tetrahydropyridine and piperidine,but also an intermediates for the synthesis of alkaloids,and is an important biologically active structure in the NADH model.Conversion to a substituted pyridine?pyridine?dihydropyridine?tetrahydropyridine by oxidation of dihydropyridine is an important backbone for the construction of piperidine by reduction or nucleophilic addition.Therefore,the synthesis of chiral substances containing pyridine has attracted great interest in recent years.Exploiting the electronic properties of pyridine to trigger asymmetric transformations of prochiral species has been used as a direct approach for accessing chiral pyridine derivatives.However,the full potential of this synthetic strategy for the construction of enantioenriched ?-functionalized pyridines remains untapped.Visible light-induced reaction has the advantages of mild conditions,green and the equipment is simple,causing more and more people's interest in visible light reaction.Based on the advantages of visible light catalysis and the importance of the pyridine skeleton,Here,we describe the first enantioselective catalytic enantioselective addition of prochiral radicals to vinylpyridines.Our group developed DPZ(dicyanopyrazine-derived chromophore compound)as the photosensitizer(DPZ shows high catalytic efficiency,usually 0.5%).Employing a chiral Br?nsted acid to activate the reaction partners and provide stereocontrol via H-bonding interactions,the enantioselective reductive couplings of vinylpyridines with aldehydes,ketones and imines were achieved,and obtained in high yields with good to excellent enantioselectivities.