Studies On The Cu-or Fe-catalyzed C-H Bond Activation Reactions For The Construction Of Nitrogen-containing Heterocyclic Compounds

C-H bond is one of the most abundant chemical bonds in nature.In recent years,the construction of heterocyclic C-N bonds through C-H bond activation has become one of the most important fields and has been developed rapidly.Currently C-H bond amination mainly focuses on the use of transition metals as the catalysts for the activation of C-H bonds.Compared with the traditional methods for the construction of heterocyclic C-N bonds,the strategy of direct C-H bond aminaition has advantages of easy availability of the starting materials,simple operation,and broad scope of substrates.More importantly,this strategy greatly shortens the synthetic steps and enhances the atom economy,thereby in line with the concept of green chemistry owing to its step economy and atom economy.On the basis of large numbers of researches on the expensive transition metal-catalyzed C-H bond amination for the construction of heterocyclic C-N bonds,this thesis mainly focused on the application of inexpensive transition metals such as Cu or Fe as the catalysts for the C-H bond amination.The Cu-or Fe-catalyzed C-H bond amination would be expected to possess even wider application in organic synthesis because Cu or Fe has advantages of low cost,easy availability,low toxicity,and environmentally benign property.The main research contents of this thesis are described as follows:1.Firstly,the thesis investigated Cu?0?/Selectfluor system-catalyzed tandem nucleophilicaddition/C-Hbondamination/annulationofo-aryl N-benzylidenebenzenesulfonamides.The reaction realized double cleavage of N-S and C-H bond and underwent intramolecular oxidative annulation to give phenanthridines by using copper as the catalyst and Selectfluor as the oxidant.The reaction has advantages of easy availability of the starting materials,mild reaction conditions,simple operation,and good compatibility of substrates.2.Then,the thesis investigated a CuI/Selectfluor?or NFSI?system-promoted intramolecular C-H bond amination/annulation of N-[1-alkyl?aryl?-1'-biphenyl]benzenesulfonamides.When CuI/Selectfluor system was used as the promotor,the reaction underwent C-H bond amination/aromatization to give 6-substituted phenanthridine as the target products;when CuI/NFSI system was employed as the promotor,the reaction underwent intramolecular C-H bond amination to afford6-alkyl?aryl?-5-phenylsulfonyl-5,6-dihydrophenanthridines as the target products.Thus,the reaction has advantages of the use of inexpensive and easily available catalyst,simple operation,and capability of tunable controlling of the reaction chemoselectivity.3.Finally,the thesis investigated Fe-catalyzed intramolecular sp²C-H bond amination/aromatization of N-[1-aryl-1'-biphenyl]benzenesulfonamides.Thus,the reaction gave 6-substituted phenanthridines as the final products by using FeCl₂ as the catalyst and Selectfluor as the oxidant.The reaction has advantages of mild reaction conditions,simple operation,and good compatibility of substrates.