Study Of Some Functionalization Reactions Based On Radical And Carbene Species

Carboncation/carbanion,radical and carbene are the common species in nature.Due to the super-reactive of radical and carbene,it’s difficult to control.Thus,limited reports involved them have been disclosed for a long time,although they have good reactivity Recently,the chemists have good comprehension in the balance between the activity and reactivity.Hence,the chemistries involved radical and/or carbene has attracted considerable interests in organic chemistry.Because of high activities of them,under the controllable conditions,many difficult chemisies could be realized through them.In this thesis,we begain our research from simple radical reactions,then moving our attention to the reaction of radical and free carbene,and terminated with metal carbeneThe first chapter is the summary of the works on specific reactions of radical,radical with carbene,and carbene,which published in recent years.In addition,the main content and architecture of this thesis is also describedIn the second chapter,an NCS mediated oxidative C-H bond functionalization for direct esterification between C(sp3)-H bond and carboxylic acids was developed.In this reaction,instead of using peroxide,NCS acts as the radical initiator.Due to the mild conditions,acetylenic acids and cinnamic acids can be tolerated while decarboxylative cross-coupling reaction was prior to occurred in previous reportsIn the third chapter,we developed NaI-mediated acetamidosulphenylation of alkenes with nitriles as the nucleophiles,providing a direct access to acetamidosulphides.Acetamidosulphide derivatives are useful chemical entities,which can be converted to many useful compounds.In the presence of NaI and peroxide,sulfur radical was given from disulfides.Then the addition to alkene with sulfur radical was occurred,followed undergo SET and Ritter reaction pathway.In the chapter 4,we realized catalyst-free S-S bond insertion reaction of donor/acceptor free carbene via a radical process,which confirmed by combined experimental and computational study.This work bridges the two speices of radical and carbene,and help me to move attention to carbene chemistry.In the chapter 5,our research based on the typical metal carbene—rhodium carbene.We found that multiple bonds could be formed via the strategy of carbene/alkyne metathesis,which have a signicant application in organic synthesis.In this context,we realized cyclopentadiene construction via Rh-catalyzed carbene/alkyne metathesis terminated with intramolecular formal[3+2]-cycloaddition.Further application of Diels-Alder additions with N-phenylmaleimide derivatives were explored as well.In the chapter 6,in our effort to expand the carbene/alkyne metathesis chemistry,we changed the carbene precursor from diazo compounds to N-sulfonyl hydrazones.However,further mechanism show that the transformation undergoes non-carbene pathway.And 3-H pyrazole was the core intermediate.Moreover,copper or thermally induced divergent outcomes for synthesis of 4-methyl 2H-chromenes and spiro-4H-pyrazoles.And the applications based on the two types of framework were explored as well.In the chapter 7,simple alkyne was directly employed as the carbene precursor.In the presence of gold catalysis and N-oxide,a-oxo gold carbene was formed.This study discloses the first examples that the Wolff rearrangement can be readily realized by a-oxo gold carbenes oxidatively generated from TBS-terminated alkynes.The thus-generated silylketenes can be isolated pure or subsequently trapped by various internal or external nucleophiles in one pot to afford a-silylated carboxylic acids,their derivatives or TBSsubstituted allenes.In this thesis,we explored some novel reactions or reactions’ pathway based on radical/carbene intermediate.Moreover,we creatively combined radical with carbene intermediates to explore some transformations.