Studies On The Direct C–H Olefination And Allylation Of Electron–Deficient Systems

Almost all organic compounds contain carbon and hydrogen elements,and C–C bonds widely exist in the organic scaffolds.The development of methods for the construction of C–C bonds has attracted considerable attention from organic chemists.Although many traditional organic reactions can realize the C–C bond construction,the relatively harsh reaction conditions,such as high reaction temperature,strong acidic or basic conditions largely restrict their applications.On the other hand,the transition metal–mediated cross–coupling represents a useful tool for the C–C bond construction,these reactions require the use of organometallic reagents or organic halides that are toxic,expensive or relatively unstable.Recently,the transition metal–catalyzed C–C bond formation from C–H bond activation has developed rapidly,and much efforts have been made in this area.To date,the related research remains a frontier of organic chemistry.This thesis mainly contains the following three aspects:Firstly,we developed a useful method for the synthesis of ortho–olefinated ketimine,which involved the [Cp*RhCl₂]₂–catalyzed,cyclic N–sulfonyl ketimine–directed C–H cleavage.The reactions tolerate numerous functional groups.Besides,some interesting molecules can be obtained from the olefinated products through further synthetic transformations.Secondly,we found that the allyl alcohol could react with electron–deficient benzoquinone in the presence of TfOH to form C–C bond.The reactions probably involved a free radical intermediate.Although the reactions proceeded under mild reaction conditions,the substrate scope of this method is limited.Thirdly,we introduced the progress of transition metal-catalyzed C–H bond activation and cross–coupling reactions.