| In recent years,with the gradual deepening of the concept of green and sustainable development,visible-light photocatalysis has become an important tool for organic synthesis with long-term application prospects,and also opens up a new idea for the development of traditional free radical chemistry.The key of photocatalytic technology is photocatalyst.Among the rich variety of photocatalysts,copper-based photocatalysts are environmentally friendly,low-priced and abundant in resources.However,there are very limited copper-based photocatalysts that can be used for visible-light-mediated organic transformations,and the developed photocatalysts still have some drawbacks that need to be addressed,such as weaker visible-light absorption,shorter excited state lifetimes and lower reduction potential.Therefore,it is of great value to explore new copper-based photocatalysts and develop the green and efficient studies of radical transformations using visible light-induced copper-catalyzed strategies,which will contribute to expanding the scope and applications of the field of copper-based photocatalysis in organic synthesis in the future.Sulfur-containing molecules occupy an important position in organic synthesis,medicinal chemistry and functional materials.Sulfonium salts,as an organic compound of sulfur(IV),can undertake various types of conversion reactions such as nucleophilic substitution reaction,sulfur ylide and elimination reaction.And they can construct various chemical bonds by selective cleavage of C-S bonds to generate radical intermediates for the efficient synthesis of drug molecules of optical or biological activity,which have great potential for application.Combining the group’s research in the fields of photochemistry,sulfur chemistry and copper catalysis,this thesis is based on visible light-induced copper-catalyzed,using sulfonium salts as alkyl radical precursors,and explores the following three new reaction modes for the construction of C-C bonds between sulfonium salts and alkynes or alkenes:(1)Developing a new method for the visible light-induced copper-catalyzed benzyl sulfoniums salts and terminal alkynes via Sonogashira coupling reaction was developed,successfully constructing C(sp~3)-C(sp)bonds.The developed method provided a highly attractive and alternative approach to various substituted alkynes,and will broaden the still limited strategies of copper complex in organic transformations.(2)Developing a new method for the visible light-induced copper-catalyzed aryl sulfonium salts and terminal alkynes via anti-Markovnikov ring-opening/Sonogashira coupling,successfully constructing sulfur-containing internal alkynyl compounds.This radical type ring-opening reaction affords a new strategy for the synthesis of internal alkynes,and will facilitate the further application of sulfonium salts in a new reaction mode of visible light-promoted organic transformations.(3)Developing a new method of visible light-induced copper-catalyzed aryl sulfonium salts and aryl olefins via radical-type ring-opening/addition/Kornblum oxidation reactions,successfully constructing ketone compounds.This synthetic strategy employs dimethyl sulfoxide(DMSO)as a nontoxic and mild oxidant,and will provide a novel and practical pathway to access various sulfur-containingα-alkyl-acetophenones. |
