Preparation Of Copper-supported Cellulose Catalyst And Study On Catalytic Amination Reaction To Synthesize Alkaloids

Achieving amination reactions is a decisive task in synthesis because structural units such as C-N bonds are ubiquitous in molecules with biological activity.Usually,C-N bond formation reactions are carried out using precious metal catalysts.However,the higher prices,as well as the toxicity of these metals have prompted a search for alternatives,especially catalysts based on non-precious metals.Apart from iron,manganese,cobalt and nickel,metallic copper offers the advantages of being more economical,less toxic and more abundant for catalytic use.Copper-catalyzed amination reactions can be used for the synthesis of new N-containing heterocyclic compounds,like some alkaloids such as indole and carbazole quinone derivatives that are highly valued by researchers due to their many physiological activities such as antitumour,anti-malarial and antioxidant properties,which play an important role in human health protection and disease treatment.As the most promising raw material for bio-based polymeric materials,cellulose,a renewable resource,is used by researchers as a functional material of different kinds due to its structure consisting mainly of crystalline arrays of parallel chains and its supramolecular ordered domains,which can be modified on the surface by other functional groups(e.g.halogens,cyano,amine,ester,carboxyl,etc.).With economy and efficiency as the starting point,cellulose and its derivatives loaded with cheap copper particles can not only participate effectively in various types of organic transformations(e.g.C-X bond construction,cycloaddition,oxidation,reduction,photocatalytic degradation,electrocatalysis,etc.),but also have a high cycle life,solving many disadvantages of homogeneous catalysts and realising green chemical reactions involving biomass materials.In this paper,a copper particle catalytic system was constructed based on cellulose and its derivatives to catalyse the synthesis of indole alkaloids and carbazole quinone alkaloids by amination reactions,achieving the efficient conversion of N-containing heterocyclic compounds.This paper not only includes the characterisation of new non-homogeneous loaded copper catalysts,but also proposes a mechanistic pathway for the synthesis of indole and carbazolquinone alkaloids,extends the application of the substrates and compares the efficiency of the homogeneous and heterogeneous reactions.In line with the theme of "atomic economy" and "step economy" in today's science,the promotion of green chemical synthesis is important for efficient energy use and reduction of environmental pollution.The specific work of this thesis is as follows.1.Design and preparation of cellulose derivatives(Cell-OPPh2)loaded copper catalysts:Using powdered microcrystalline cellulose as the initial material,the compound diphenylphosphonium chloride(Ph2PCl)was added dropwise to a pyridine solution of cellulose for modification to obtain white solid Cell-OPPh2 functionalised cellulose,which was then solidly loaded with anhydrous copper acetate particles to successfully construct The cellulose copper catalytic system was successfully constructed.A systematic characterisation of this new cellulose Cu-catalyzed complex was carried out using XRD,FT-IR,TG,SEM,TEM,XPS and ICP-AES.The results showed that the modified cellulose had been successfully loaded with copper particles,in which the elemental copper was mainly present in the divalent form,and that the cleavage temperature was increased compared to that of Cell-OPPh2,reaching 245?.Finally,the ICP-MS of the analysed samples calculated and derived the elemental copper content of the cellulose-based copper catalyst to be 4.76%.The reaction efficiency of some classical copper-catalyzed amination reactions(Chan-lam reaction,Ullmann reaction)with the participation of this catalyst was also investigated,as well as the activity of the catalyst used.Firstly,one of the Cu/Cell-OPPh2 catalysts was tested in the Chan-Lam coupling reaction,which not only gave high yields(96%)but was also easily recoverable and was repeated eight times with little effect on its catalytic activity,proving its good stability.Also,the Ullmann coupling reaction gave the product 1-phenylimidazole in an excellent yield of 93%,which could be recycled for six cycles.2.Copper-catalyzed synthesis of indole alkaloids from cellulose derivatives(Cell-OPPh2)loading.In this paper,a one-pot synthesis of indole derivatives was achieved by a cellulose-based copper-catalyzed test of intermolecular tandem Chan-Lam coupling reactions and intramolecular dehydrogenated C-C coupling reactions using aromatic boronic acids and alkenamines as raw materials.Using(Z)-3-phenyl-3-aminoethyl acrylate as a substrate,a series of controlled variables with phenylboronic acid were used to determine the optimum reaction conditions for the method:initial Chan-Lam arylation reaction for 24 h to give ester(Z)-3-arylaminoacrylate intermediates.These arylation intermediates do not need to be purified,but can be further reacted in a solvent mixture(DMF/DMSO=2:1)at 130? for intramolecular oxidative cross-dehydrogenation coupling to give C3-functionalised polysubstituted indole derivatives in a "one-pot" process.The catalyst activity and generality of the catalyst were investigated and the Cell-OPPh2-Cu catalyst could be recycled for 6 cycles and 25 polysubstituted indole derivatives were successfully synthesized in 40%-60%yields.The method is characterized by novel and innovative method,high regioselectivity and recyclable catalyst,which not only saves production cost but also has potential applications in both organic synthesis and research of biological materials.3.Cellulose derivatives(Cell-OPPh2)loaded with copper-catalyzed synthesis of carbazolequinone alkaloids.In this paper,a new one-pot method was developed for the synthesis of a variety of carbazolquinone derivatives via the cellulose-based copper-catalyzed C-N bond formation of benzocarbazoldione substrates.The whole process is a copper-catalyzed intramolecular oxidative amination,and the use of the green oxidant O2 certainly adds to the highlight of the process.Also,in this paper,a cellulose-based Cu catalyst was screened and compared with a conventional homogeneous catalyst,which could increase the yield of the reaction to 74%.Under the optimised conditions,the range of substrates was investigated and the results showed that the method has good general applicability,with a total of 32 carbazoquinone derivatives synthesised in a maximum yield of 93%and a wide range of substrates and pharmaceutical properties,and can be used in the synthesis of new drug skeletons.