Copper-catalyzed Oxyphenylation Of Alkyne Cleavage And Visible-light-promoted Polyfluoroalkyl Alkenylation Of Alkenes

Alkenes and alkynes,as important synthons in organic chemistry,have the advantages of abundant availability and low price.In addition,because they contain unsaturated carbon-carbon bonds,various classical reactions such as oxidation,reduction,halogenation,addition,and polymerization can smoothly take place,thereby introducing corresponding functional groups.In recent years,the difunctionalization of alkenes(alkynes)can economically introduce two target functional groups in one step and rapidly construct the value-added molecules,which has been widely used in organic synthesis.At present,despite remarkable achievement obtained in transition metal-catalyzed,visible light-promoted and electrochemical difunctionalization of alkenes(alkynes),these methods generally involve expensive catalysts,harsh reaction conditions,complicated operation,and low reaction selectivity.Therefore,the development of green,efficient and highly selective difunctionalization of alkenes(alkynes)still attracts much attention in the field of organic synthetic chemistry.Although alkynes are one of the most basic reagents in synthetic chemistry,reactions for the cleavage of the carbon-carbon triple bonds are rarely demonstrated.Traditionally,the cleavage of the carbon-carbon triple bonds requires stoichiometric organometallic reagents or strong oxidants.Based on this research background,we explore the copper-catalyzed oxyphenylation of alkynes through carbon-carbon triple bond cleavage in Chapter 2.The difunctionalization of alkynes can be rapidly and efficiently carried out at 80 °C for 4 hours via a tandem-migration radical process with alkynes as model substrate,acetonitrile as solvent,N-fluorobisbenzenesulfonamide as free radical precursor and aryl source,copper sulfate as catalyst,tert-butyl hydroperoxide as oxidant,and nitrogen as reaction atmosphere,providing a series of the desired aromatic ketones.Isotopic experiments show that water plays an important role in this reaction.The developed alkyne difunctionalization has the advantages of mild reaction conditions,simple operation,use of cheap and readily available reagents,high regioselectivity,and broad substrate scope.Because of good pharmacodynamics and kinetic properties,fluorinated organic compounds are prevalently applied as small molecule drugs.Existing reports of1,2-difunctionalization of alkenes for the introduction of fluorine-or fluoroalkyl-containing groups mainly rely on transition metal catalysis,photoredox and electrochemistry.Although these methods have been widely developed,they still suffer from some limitations.For example,the reactions usually require external transition metal catalysts(photocatalysts),corresponding ligands or electrochemical devices,resulting in harsh reaction conditions and complicated operations,which restricts their further synthetic applications to a certain extent.In his context,we explore visible light-promoted perfluoroalkylalkenylation of alkenes without external photocatalysts in Chapter 3.The perfluoroalkylalkenylation can be efficiently carried out at room temperature for 20 hours with 1,2-dichloroethane as solvent,2-anilino-1,4-benzoquinone as model substrate and photosensitizer,perfluoroiodobutane as fluorine source,cesium carbonate as base,and nitrogen as reaction atmosphere,providing a variety of perfluoroalkylated naphthoquinonesin good yields and excellent regioselectivity.The developed alkene difunctionalization features simple operation,mild conditions,use of cheap and readily available reagents,and a wide range of substrates.More importantly,the reaction does not require external photocatalysts.