Nickel-catalyzed Reductive Homo-coupling And Cross-coupling Reactions

Transition metal-catalyzed cross-coupling methodology has become indispensable for modern chemistry,including the synthesis of pharmaceuticals,natural products and polymeric materials.Although cross-coupling reactions now represent a mature technology,there is still a lot of research in this field aimed at improving the scope of these reactions,developing more effective catalysts,and making the reactions more practical.Nickel-catalyzed reductive coupling reactions have been extensively studied in the construction of carbon-carbon and carbon-hetero bonds,etc.Among them,the reductive coupling reaction between electrophiles avoids the preparation of organometallic reagents,with a wide range of substrates under mild conditions.This dissertation describes the formation of a series of transformation carbon-carbon bonds and carbon-hydrogen bonds in the catalytic system using nickel as the catalyst and manganese as the reducing reagent.Our work has been divided into four parts:(1)The nickel-catalyzed reductive cross-coupling reaction of allyl quaternary ammonium salts and halogenated aromatic hydrocarbons was developed,and C(sp~2)-C(sp~3)bonds were constructed under mild conditions,which broadened the synthesis methods of linear aromatic hydrocarbons.(2)The nickel-catalyzed denitrification and protonation reaction of benzyl quaternary ammonium salt has been developed,and the C-H bond is constructed by in-situ reductive protonation,and the selective C-N bond cleavage is realized.(3)In a reducing system,the activation of the carbon-chlorine/carbon-bromide bond on chlorinated/bromoaromatic hydrocarbons is achieved by nickel catalysis,and the C(sp~2)-C(sp~2)bond is constructed through self-coupling,which can tolerate a variety of functional groups,Synthesize biphenyl derivatives with excellent yield.It provides another method for reductive coupling reactions involving chlorinated aromatic hydrocarbons in the future.(4)The self-coupling reaction of chloroalkanes is used to construct C(sp~3)-C(sp~3)bonds with mild reaction conditions and a wide range of substrates.The above transformations have boarden the scope of nickel-catalyzed reductive coupling system,and will be an effective supplement to traditional electrophiles-nucleophile cross-coupling reactions.