Suzuki Single Coupling Reaction Of Symmetrical Dihaloaryl Hydrocarbons Catalyzed By Cross-linked Cyclodextrin Polymer-supported Palladiu

Supramolecular catalysis is one of the important research directions in the intersection of supramolecular chemistry and catalytic chemistry.As a natural macrocyclic supramolecular compound,cyclodextrin has an outer hydrophilic and inner hydrophobic cavity,showing good molecular recognition ability.Cross-linked cyclodextrin compounds based on cyclodextrin synthesis have excellent applications in separation and enrichment,drug delivery and reaction catalysis.Symmetrical dihalogenated aromatic hydrocarbons（heteroaromatics）are an important class of organic compounds.The reaction of two C-X bonds can synthesize a series of pharmaceutical intermediates and organic luminescent materials.However,when the two C-X bonds have the same chemical environment,the key to monoarylation is to prevent the second oxidative addition of monoarylated products.In this paper,a cross-linked cyclodextrin polymer was designed and synthesized by Cu AAC reaction.While retaining the cyclodextrin cavity,a large number of triazole rings were formed as metal coordination sites,which effectively dispersed the metal to form nano-metal particles with high catalytic ability.The synergistic effect of the two makes the cross-linked cyclodextrin polymer of the coordinated metal have selective catalytic ability.The specific work of this paper is as follows:Firstly,four kinds of cross-linked cyclodextrin polymers CD-P-1,CD-P-2,CD-P-3 and CD-P-4 were designed and synthesized,and used as ligands to study the Suzuki single coupling reaction of symmetrical dihalogenated aromatic hydrocarbons and heteroaromatic hydrocarbons.The catalyst screening showed that the catalyst CD-P-3-Pd（II）corresponding to the crosslinked cyclodextrin polymer 3 had the best catalytic activity,and it was characterized and analyzed by FT-IR,SEM,TEM,XPS,ICP-AES and XRD.After condition screening,the mixed solvent of40°C,Cs₂CO₃,CD-P-3-Pd（II）,1,4-dioxane and water was determined as the optimal reaction condition to catalyze the Suzuki single coupling reaction of symmetrical dihalogenated reagents.Seventeen substrates were expanded,and three of them were applied to synthesize triaryl compounds with potential application value.In this process,a pre-inferred possible reaction mechanism was shown,that is,the molecular recognition ability of cross-linked cyclodextrin polymers can effectively prevent the second oxidative addition of monoarylated products.The inclusion experiments ofβ-CD with substrates,single coupling products and double coupling products were verified,and the reaction mechanism was further proved by Job curve and bonding ability experiments.In addition,the catalyst showed excellent catalytic activity in the conventional Suzuki coupling reaction.Under mild reaction conditions,seven products with different substituents can be obtained in a short time with 60%-90%separation yield.