Synthesis Of Magnetic Nanoparticles Or MCM-41-Immobilized Phosphine-gold(?) Complexes And Their Catalytic Properties

This dissertation reported synthesis of magnetic nanoparticles or MCM-41-immobilized phosphine gold???complexes and their catalytic properties.The works were mainly divided into the following four parts:1.The silica-coated Fe₃O₄ nanoparticles?Fe₃O₄@SiO₂?was condensed with 2-?diphenylphosphino?ethyltriethoxysilane in toluene to produce diphenylphosphinofunctionalized Fe₃O₄@SiO₂?Fe₃O₄@SiO₂-P?.The latter was reacted with AuCl in methanol at reflux for 24 h,and then treated with AgOTf in dichloromethane at room temperature for 2 h to give the magnetic nanoparticles-immobilized phosphine gold???complex?Fe₃O₄@SiO₂-P-AuOTf?.This heterogeneous gold???complex was characterized by TEM,XRD and EDS techniques and applied to ring expansion reaction of unactivated alkynylcyclopropane with sulfonamides leading to?E?-2-alkylidenecyclobutanamines.The results showed that the supported gold???catalyst exhibited high catalytic activity and can be recycled for 10 times without significant loss of catalytic activity.2.The tandem three components reaction of aldehydes,terminal alkynes and orthoformates was investigated in dichloroethane in the presence of the supported catalyst Fe₃O₄@SiO₂-P-AuOTf,giving the corresponding propargylic ether in good yields.The results indicated that the activity of this heterogeneous gold???catalyst was comparable to that of homogeneous Ph3 PAuOTf and its catalytic efficiency remains unaltered even after recycling six times.3.The condensation reaction of triethoxysilyl-functionalized triphenylphosphine ligand with mesoporous MCM-41 in toluene,followed by silylation with Me3 SiCl afforded the triphenylphosphine-functionalized MCM-41?MCM-41-PPh3?.The latter reacted with Me2 SAuCl in dichloromethane to generate the MCM-41-immobilized phosphine gold???complex?MCM-41-PPh3-AuCl?.The new heterogeneous gold???complex was characterized by XRD,EDS and ?CP-AES techniques and applied to direct Csp²-Csp bond functionalization of aryl-substituted alkynes leading to amides.The results showed that,in the presence of TFA and H2 O,nitrogenation of arylsubstituted alkynes with TMSN₃ proceeded smoothly at 60 oC using MCM-41-PPh3-AuCl and Ag2CO3 as catalysts,affording a variety of amides in good to excellent yields.More importantly,this supported gold???catalyst can be recycled for six timeswithout significant loss of activity,which providing a novel,practical and green route to amides from alkynes.4.The annulation reaction of propargylic aldehydes with 2-aminopyridines was investigated in dichloromethane?DCM?in the presence of Fe₃O₄@SiO₂-PPh3-AuCl and AgSbF6.The results indicated that this heterogeneous gold???catalyst exhibited high catalytic activity,and the reaction proceeded smoothly at room temperature to give a variety of imidazo[1,2-a]pyridine derivatives in good yields.This supported gold???complex could be reused for many times without any decrease in activity,providing a new,practical and green approach for the synthesis of imidazo[1,2-a]-pyridine derivatives.