Visible-Light Photoredox-Catalyzed Iminyl Radical Formation To Synthesize Isoquinolines By N-H Cleavage

Heterocyclic compounds,which are main frameworks of natural products and bioactive molecules,widely distributed in synthetic molecules,pharmaceuticals and functional materials.Hence,the new strategy of building C-N bonds have been investigated most in-depth in the past few decades,many novel methods have been developed.Nitrogen-centered free radicals play an important role in chemical transformation,since they distinct intermediates from versatile compounds.This thesis mainly a visible-light photoredox-catalyzed formation of isoquinoline compounds by dehydrogenative coupling of imine and alkyne with H₂ escaped as byproduct,when Acr⁺-Mes ClO₄^-and a new Co catalysis was used as co-catalysis.This thesis contains two chapters:Chapters I,we presented a smart review on the recent progresses of photo-,electro-,transition-metal catalytic formation of nitrogen-centered radicals and the utilization of N-heterocycles and nitrogen-centered free radicals in organic synthesis.Chapters II,we have developed the visible-light photoredox-catalyzed iminyl radical formation by N-H bond cleavage.The photosensitizer,catalyst,solvent were screened under template conditions employing bis?4-methylphenyl?methanimine and 1,2-diphenylacetylene.Finally,this approach was successfully applied in the syntheses of isoquinoline compounds undergo visible-light photoredox-catalyzed process when Acr⁺-Mes ClO₄ as photosensitizer,a new Co salt as catalysis,and DCM employed as solvent.The result of experiments showed that iminyl radical formation by N-H cleavage is key intermediate,which initiates the cascade C-N/C-C bonds formation.We find the photocatalysis oxidatively quenching and reductively quenching simultaneously by two SETs,so proposed a fessible mechanism based upon emission-quenching experiments,cyclic voltammetry experiments and quantum yield experiments.We developed its application in the synthesis of isoquinolines.Herein,an efficient method for synthesis of various N-heterocycles in high atom economy is developed at ambient temperature.