Synthesis Of Mesoporous MCM-41-immobilized NHC-gold(I) Complexes And Their Applications In The Construction Of Carbon-carbon And Carbon-sulfur Bonds

In this dissertation,we investigated the synthesis of mesoporous material MCM-41-immobilized sterically demanding nitrogen heterocyclic carbene-gold(I)complexes and their catalytic behaviors in carbon-carbon and carbon-sulfur bond formation reactions.The research work is mainly divided into the following three parts:1.Firstly,a silylated NHC-Au Cl complex,(1,3-bis(2,6-diisopropyl-4-(3-(triethoxysilyl)propyl)phenyl)-2,3-dihydro-1H-imidazol-2-yl)gold(I)chloride [(Et O)3SiIPr Au Cl] was prepared according to a reported procedure from commercially readily available starting materials.Then the condensation of(Et O)3Si-IPr Au Cl with mesoporous MCM-41 at 110 oC in toluene for 24 h provided the MCM-41-immobilized sterically demanding NHC-gold(I)chloride complex(MCM-41-IPr Au Cl).Finally,MCM-41-IPr Au Cl was treated with different silver salts(Ag X = Ag OTf,Ag NTf2,Ag BF4,Ag PF6,and Ag Sb F6)in DCM at room temperature to give the MCM-41-immobilized sterically demanding NHC-gold(I)complexes [MCM-41-IPr Au X,X = OTf,NTf2,BF4,PF6 and Sb F6)as gray powders.The MCM-41-IPrAuNTf2 complex was fully characterized by different physico-chemical techniques such as ICP-AES,XRD,BET,EDS,and XPS.2.We studied the stereoselective thioallylation reaction of electron-deficient alkynes with allyl sulfides towards tri-and tetrasubstituted functionalized vinyl sulfides by using MCM-41-IPrAuNTf2 as the catalyst.The results showed that in the presence of 1-2 mol% the MCM-41-IPrAuNTf2 complex,the thioallylation reaction of a range of electron-deficient alkynes with various allyl sulfides proceeded smoothly under mild conditions with high regio-and stereoselectivities,providing a variety of stereodefined tri-and tetrasubstituted functionalized vinyl sulfides in good to excellent yields.The new heterogeneous MCM-41-IPrAuNTf2 catalyst exhibits a comparable activity to homogeneous IPrAuNTf2 complex and can be recovered via a simple filtration process and reused at least seven consecutive cycles without any apparent loss of its catalytic activity and selectivity.Therefore,the current method offers a novel,highly efficient,practical and green route to tri-and tetrasubstituted functionalized(Z)-vinyl sulfides.3.We investigated the application of MCM-41-IPrAuNTf2 in the cascade annulation of anthranils with propargyl silyl ethers leading to 2-aminoquinoline derivatives.It was found that in the presence of 5 mol% MCM-41-IPrAuNTf2,anthranils and propargyl silyl ethers could undergo the sequential ring opening/1,2-H-shift/ protodeauration/Mukaiyama aldol cyclization reaction smoothly under mild conditions,regiospecifically affording a range of 2-aminoquinoline derivatives in high yields.The heterogeneous gold(I)catalyst can be easily separated from the product and recovered through a simple filtration process,and recycled up to eight times without significant loss of catalytic activity.Thus,our work provides a novel,practical and green method for the construction of 2-aminoquinoline derivatives.