Investigation The Process Of C-H Activation Reaction Directed By 5-nitropyrimidine And Synthesis Of Chiral Phase Transfer Catalyst

Due to their superior catalytic properties,transition metal catalysts are widely used in organic synthesis,such as the construction of carbon-carbon bonds,carbon heteroatoms bonds.The transition metal catalyzed carbon-hydrogen bond(C-H)activation functionalization which was assisted by directing group was received great attention owing to its convenient and high efficience.Since transition metals(palladium,nickel,etc.)can be well coordinated with nitrogen,oxygen,phosphorus and other heteroatoms,the development of C-H activation reactions assisted by these directing atoms has been given non-stop concern.Tremendous attention has been put onto finding a novel directing group which is easy to introduce and easy to remove during the C-H activation reaction.This dissertation focuses on using an easily accessible 5-nitropyrimidine as the directing group to achieve palladium catalyzed hydrocarbon activation reactions,and the synthesis and application of chiral phase transfer catalysts was also presented.The content consists of the following three parts:I.Study on C-H Acetoxylation Reaction and Preparation of 2-aminophenol and its Derivatives5-Nitro-N-phenoxylpyrimidin-2-amine was used as the substrate,palladium acetate as the catalyst and iodobenzenediacetic acid as the oxidant in the reaction.The introduction of a assisting group,the C-H activation functionalization and the removal of the assisting group can be achieved at the same time in a one-pot.Under the optimized conditions,the corresponding products can be obtained in gram scale.The results of the study indicate that 5-nitropyrimidine can act as formally temporary assisting group in this reaction.This provides an alternation to run the directing group assisted C-H activation reaction of aniline derivatives.II.Study on C-H Acetoxylation and Preparation of Pyrocatechol,Benzene-1,2,3-triol and Their Derivatives.Phenol and its derivatives are important building blocks in chemical drugs and natural products.They are widely used in dye chemistry,material sciences and so on.We directly used various kinds of simple phenols to gain more functionable derivatives.In this project,the 5-nitropyrimidine is used to generate intermediate 5-nitro-2-phenoxypyrimidine,which can be introduced one or two acetoxy groups according to use the different amount of the oxidizing agent.After optimizing the reaction condition,we applied the reaction to various substrates,including phenol with free alcohol,etc.This reaction has few characters: such as 1)structurally diversified phenol derivatives can be successfully ortho-acetoxylated under similar one-pot reaction condition;2)both the C-H functionalization and the mild directing group removal procedure have high function group tolerance;3)the transformation from phenol derivatives to pyrocatechol,benzene-1,2,3-triol and their Derivatives is amenable to a gram-scale synthesis and the practical auxiliary,5-nitropyrimidine,was successfully applied as a transient directing group during introduction of DG,C-H functionalization and removal of DG.III.Synthesis of Chiral Phase Transfer Catalysts and Their Application in Asymmetric SynthesisIn this paper,Chiral Dicationic Bisguanidinium and Halogenated Pentanidium Salts were used as chiral phase transfer catalysts in the reactions to make chiral di-ols.From the corresponding experiment,the chiral dicationic bis-guanidinium salt is found to be a highly selective chiral catalyst,and the initial exploration has yielded moderate enantiomeric excess(ee)values.