Application Of Hantzsch Esters In Photoredox Catalysis

Photoredox catalysis has recently received extensive attention as a tool for synthetic organic chemists,its has already been applied to the development of a wide range of new carbon-carbon bondforming reactions and also proven to be a valuable tool for the construction of complex molecules.Hantzsch esters has been widely studied since its' discovery in 1882,and behaves as a potential reducing reagent in visible light catalysis.However,the reaction of C-4 substituted Hantzsch Esters by visible light-induced photoredox catalysis has not been reported.Additionally,the unqine property of Hantzsch esters in metal free visible light-induced photoredox catalysis is underestimated in.With these points in mind,what this thesis addressed were listed as below:1.Building congested ketone:substituted Hantzsch Esters and Nitriles as alkylation reagents in photoredox catalysis.We reported the first alkyl transferring reaction involving 4-alkyl Hantzsch esters and their nitriles analogues constructing products with a single all-carbon quaternary center,as well as two contiguous centers,via visible light-induced photoredox catalysis.This chemistry was applied in the synthesis of a common precursor of a class of hydroxysteroid dehydrogenase inhibitors 2.Hantzsch Ester as a photosensitizer for Visible-Light-Induced debromination of vicinal dibromo compoundsWe developed an efficient protocol for deprotection of vicinal dibromo compounds to afford alkenes.With the help of an inorganic base,the Hantzsch ester acts as a self-activating reductant under visible-light irradiation.The tolerated substrates include styrene,?,?-unsaturated compounds,and unfunctionalized alkenes.Robustness screening demonstrated that the protocol is compatible with a variety of functional groups.Mechanistic experiments revealed that the base is critical for activation of the Hantzsch ester.