Study On Construction Of Furan,Indole And β-carboline Derivatives Catalyzed By Mesoporous Materials-supported NHC-gold(Ⅰ) Complexes

This dissertation has investigated the preparation of mesoporous materials MCM-41 or SBA-15-immobilized nitrogen heterocyclic carbene-gold（Ⅰ）complexes and their application in catalytic construction of furan derivatives via intramolecular oxidative cyclization of 1,4-diyn-3-ols or interemolecular oxidative cyclization of diynones with alcohols and 2-aminoindole or 3-amino-β-carboline derivatives via heterocyclization of ynamides with benzyl or indolyl azides.The main research works are divided into three parts as follows:1.The mesoporous material MCM-41-supported sterically demanding NHC-gold（Ⅰ）complex[MCM-41-IPr Au OTf]was prepared and characterized.An efficient heterogeneous gold（Ⅰ）-catalyzed cascade oxidation/1,2-alkynyl migration/cyclization reaction of 1,4-diyn-3-ols has been developed.The results indicate that the oxidative cyclization reaction proceeds effectively in toluene at room temperature by using 3mol%of MCM-41-IPr Au OTf as catalyst and 3,5-dichloropyridine N-oxide as oxidant and offers a general and practical route for the synthesis of a wide variety of3-formylfurans in good to excellent yields from readily accessible starting materials.This heterogenized gold（Ⅰ）catalyst can be facilely recovered via a simple centri-fugation process and reused more than six times without any significant loss of its catalytic efficiency.2.We have investigated the application of MCM-41-supported sterically demanding NHC-gold（Ⅰ）complex[MCM-41-IPr Au NTf₂]in the oxidative cyclization of diynones with alcohols via a nucleophilic attack to the carbonyl group of theα,α’-dioxo gold carbene and subsequent 1,2-alkynyl migration.The results show that the oxidative cyclization reaction proceeds smoothly in 1,2-dichloroethane at 60℃ by using 8 mol%of MCM-41-IPr Au NTf₂as catalyst and 3,5-dichloropyridine N-oxide as oxidant and provides a general and practical method for the assembly of a wide variety of functionalized furan-3-carboxylates in good to excellent yields.Importantly,this heterogenized gold（Ⅰ）complex is easy to recover by centrifugation of the reaction mixture and is recyclable up to seven times without any apparent loss of its catalytic activity.3.The mesoporous material SBA-15-supported sterically demanding NHC-gold（Ⅰ）complex[SBA-15-IPr Au NTf₂]was prepared and characterized.A heterogeneous gold（Ⅰ）-catalyzed heterocyclization of ynamides with benzyl or indolyl azides has been investigated by using SBA-15-IPr Au NTf₂as catalyst.It was found that in the presence of 5 mol%SBA-15-IPr Au NTf₂,the heterocyclization reaction proceeds smoothly in DCE under mild conditions,delivering a wide range of valuable2-aminoindoles or 3-amino-β-carbolines in mostly good to excellent yields with high regioselectivity.Importantly,the new heterogenized NHC-gold（Ⅰ）complex exhibits a comparable catalytic activity to IPr Au NTf₂and is facile to recover by centrifugation of the reaction mixture and can be reused at least seven times without any appreciable loss of its catalytic activity.