Decarboxylative Sulfenylation Of Amino Acids Via Metallaphotoredox Catalysis

In recent years,the emergence of visible light-mediated photoredox catalysis has led to the discovery of many unique and valuable chemical reactions.As an effective tool to activate small molecule substrates,photoredox catalysis has become the forefront of modern organic chemistry research.Transition metal catalysis could led to chemical properties and controllable chemoselectivity in organic reactions.Recently developed metallaphotoredox catalysis has successfully achieved many transformations that cannot be achieved in a single catalytic mode.Carboxylic acid is a cheap and easily accessible chemical raw material.It is widely used in chemical synthesis.Numerus valuable transformations are realized via visible light catalyzed decarboxylation.Metallaphotoredox catalysis provides a new reaction mode for decarboxylation reactions under mild conditions.This thesis is divided into three chapters.The first chapter briefly introduces the recent advance of visible light catalysis.The recent development of organic transformations realized by metallaphotoredox(such as Pd,Ni,Cu,Au)and the decarboxylation of carboxylic acids under visible light is reviewed in Chapter 1.In chapter ?,we developed a new type of C-S bond construction method.Combining Ni-catalysis and visible light photoredox catalysis,we have developed the first decarboxylative sulfenylation from amino acids and lactic acid.In this reaction,the alkyl radicals were released in visible light catalysis.Two reaction modes are involved:on the one hand,the alkyl radicals undergo a free radical chain reaction with a sulfurization reagent to form the sulfides.On the other hand,when the nickel catalyst was added,the alkyl radicals are captured by the nickel catalyst to form a reactive Ni(?)intermediate.Further reductive elimination produces the sulfide product.This photocatalytic reaction shows advanced features such as odorless thiolation by avoiding the use of malodorous thiols and very mild conditions.In chapter ?,preliminary attempts were made to construct asymmetric C-S bonds from halogenated alkanes catalyzed by nickel.Although the expected results have not been obtained,the research provides some fundamental support for the synthesis of asymmetric sulfides.