Visible-light Photoredox-involved Cooperative Catalysis In Asymmetric Synthesis

Energy is one of material foundations of human campaign.The development and application of energy is a major issue facing scientists from around the world today.Solar energy is a kind of renewable green energy.With the decrease of fossil fuels,solar energy has become an important part of human energy.How to efficiently convert solar energy into chemical energy is a subject that chemists have been exploring.Since 1886,Italian chemists professors Ciamician and Silber have studied photochemistry.Visiblelight photoredox catalysis is a single electron transfer process that utilize the oxidation or reduction ability of photosensitizer when it transits to the excited state under visible light irradiation.The intermediates generated in the visible-light photoredox catalytic cycle have high reaction activity.Therefore,it is difficult to control the stereoselectivity.The characteristics of organocatalysis are mild conditions,simple operation,atomic economy,environmental friendliness and so on.Combining visible-light photoredox catalysis with organocatalysis,the asymmetric reaction of visible-light photoredox catalysis can be realized with high efficiency and high enantioselectivity under the mild conditions.This disertation is devoted to the study of visible-light photoredox catalysis and organocatalysis in the way of synergetic catalysis or relay catalysis to realize the asymmetric reaction involving the free radicals.The research contents are as follows:In the first part,acyl radicals generated from α-ketoacids under the action of visible light,the asymmetric radical hydroacylation of enals has been achieved between the chiral amine and photoredox.The range of this method is applied through the reactions of all kinds of enals with α-ketoacids.This strategy provides an efficient way accessing the challenging 1,4-dicarbonyl compounds in an enantioselective manner under the mild conditions.In the second part,the chiral fluorides were synthesized by sequential organocatalyzed desymmetrization of 3-substituted glutaric anhydrides and photoredox catalyzed decarboxylic fluorination of the resultant chiral carboxylic acids.This strategy provides an efficient way to access chiral fluorinated compounds in a highly enantioselective manner under the mild conditions.In the third part,the asymmetric radical allylic alkylation has been achieved between the photoredox and palladium catalysis.Alkyl radicals generated from 4-methylanisole under the action of visible light.The target product was obtained with good yield,excellent enantioselectivity and excellent regional selectivity.