Polarity Umpolung Strategy For The Radical Alkylation Of Alkenes

Carbon-carbon(C-C)bonds are the basic framework of organic compounds Alkylation of olefins provides an efficient strategy for construction of the C-C bonds and lengthening of the carbon chains.In recent years,radical-mediated alkylation of the alkenes has attracted wide attentions of chemists due to its advantages of mild conditions,good functional group compatibility,and wide range of substrates.Nowdays,this protocol is mainly restricted to activated olefins due to the inert reactivity of unactivated olefins,and free radical-mediated alkylation of unactived alkenes remains challenging and was rarely reported.Herein,we disclose a conceptually novel "polarity-umpolung"strategy for radical alkylation of alkenes using a portfolio of easily-accessed dual-function alkylating reagents.The main work in this thesis is employing this strategy to achieve alkylation of activated olefins,alkylation of non-activated olefins,and multi-component alkylation of olefins.The full text mainly includes the following four parts:The first part summarizes the research progress of radical-media ted alkylation of olefins and fuctional group migration strategies.This is the basis and significance of this thesis.The second part introduces the research on radical-mediated polarity umpolung and docking migration strategy to achieve alkylation of activated olefins.The reaction shows wild conditions and the late-stage modification of complex natural moleculesThe third part introduces the radical-mediated polarity umpolung strategy to achieve alkylation of unactivated olefins.The reaction maked nucleophilic alkyl radicals into electrophilic alkyl radical skillfully by polarity-reversal strategy.It was easier to addition to the electron-rich aliphatic olefin,which converted the intermolecular reaction into the intramolecular,and then went through the intramolecular heteroaryl migration,SO2 extrusion,and the alkyl radical is terminated to obtain an alkylated product.This reaction is suitbale for a wide range of substrates with good functional groups tolerance,offering an efficient approach for the late-stage modification of complex natural products and drug molecules.The fourth part introduces the research on radical-mediated polarity umpolung and docking migration strategy to achieve multi-component alkylation of alkenes.The reaction employs various radical trappers to terminate the alkyl radical intermediate for multi-component alkylation of alkenes.This process features mild conditions,high diversity of products,and introduction of functional groups at specific sites.In conclusion,we have developed a novel "radical-polarity umpolung" strategy to achieve the radical alkylation of alkenes,which is a challenging issue in organic radical chemistry.The reaction features mild photocatalytic conditions,broad functional group tolerance and high product diversity which also suits for the late-stage modification of complex natural product and drug molecules,providing an efficient approach for the synthesis of aliphatic compounds.