Synthesis Of N-glycosides Based On Dehydroxylative Sp~3 C-N Coupling Via Dual Copper And Photoredox Catalysis

N-glycosides have widespread applications in chemical biology and drug development.However,existing methods generally involve two-electron polar reactions that require strong Lewis acids or bases.This thesis is dedicated to developing simple and efficient radical strategies for the synthesis of N-glycosides,as follows.A new method based on photo/copper synergistic catalytic dehydroxylation coupling for the synthesis of N-glycosides was developed.The reaction uses Nheterocyclic carbene-activated 1-hydroxy carbohydrates and N-containing heterocycles as starting materials,inexpensive copper salts as catalysts,and 4-Cz IPN as photosensitizers to construct C-N bonds directly under visible light irradiation without heating.The method has a broad substrate scope(81 substrates)and can be applied to various important N-containing heterocycles(e.g.,indazole,carbazole,pyrazole,indole,azaindole,pyrrole,purine,pyrimidine,cyclolactam,etc.)and pyranose and furanose with different protecting groups(e.g.,ribose,deoxyribose,glucose,mannose,galactose,rhamnose)in yields up to 92%,can be used for glycosylation modification of N-containing heterocyclic drugs.In addition,the method exhibits good stereoselectivities,giving 1,2-trans products for furanose substrates and α-products for pyranose.Mechanistic studies suggest that the target products may be obtained by the oxidative addition of the sugar radicals to the copper(II)complex followed by reductive elimination.The work in this thesis provides a new pathway for the synthesis of N-glycosides and facilitates the study of related medicinal chemistry and chemical biology.