Reaction Of P-Nitrobenzaldehyde And Unsaturated Esters Catalyzed By Irdium And Nhc Carbene And Design,synthesis And Application Of Ruthenium Catalysts Supported On Magnetic Fe₃O₄ Nanoparticles

Transition metal catalysis and heterocyclic nitrogen carbene catalysis are noticeable catalysis in organic chemistry,many conversions have been achieved,particularly in asymmetric catalysis.Recently,cooperated catalysis has been gradually entered into the researchers' eyes,which can be used to design an innovative and selective co-catalyst system by combining two catalysts.This refined strategy can permit chemical transformations unmanageable by either of the catalysts.Since the cooperated catalysis research catch people's attention,the cooperated catalysis systems has also achieved an unprecedented development.The main cooperated catalysis systems include: bimetallic catalytic system,heterocyclic nitrogen carbene and Lewis acid or Bronge acid-base dual catalytic system,transition metal and small organic molecular catalyst co-catalytic system,transition metal and heterocyclic nitrogen co-catalytic system.In this paper,it mainly includes reaction of p-nitrobenzaldehyde and esters catalyzed by iridium and heterocyclic nitrogen carbene and the design,synthesis and application of ruthenium catalysts supported on magnetic Fe₃O₄ nanoparticles.The main work include two parts as follows:First part is the reaction of p-nitrobenzaldehyde with ?,?-unsaturated esters by the dual catalysis of iridium and heterocyclic nitrogen carbene.The study was based on the properties of the iridium catalyzed allylation reaction,the nitrobenzaldehyde and unsaturated carbonates was chose as substrates,and two catalytic systems was developed.The 3-trimethylphenyl-5,6,7,8-tetrahydro-4H-cycloheptatriene [d] thiazol-3-onium perchlorate was chose as the NHC carbene catalyst,[Ir?cod?Cl]2 or [Ir?coe?2Cl]2 as the metal catalyst,the best base is potassium carbonate or cesium carbonate.Both of the catalytic systems can catalyze the reaction of racemic allyl carbonate with p-nitrobenzaldehyde and produce two chiral carbonates with high ee value.These two catalytic systems have wide range of substrates applicability.Second part is the design,synthesis and application of ruthenium catalysts supported on magnetic Fe₃O₄ nanoparticles.To increase the activity and recyclability of the catalysts,recoverable ruthenium catalysts supported on silica-coated or uncoated magnetic Fe₃O₄ nanoparticles were designed and applied in ring-closing metathesis and cross metathesis reactions.The catalysts were very active and the reaction could be finished within 30 minutes.Ruthenium catalyst supported on silica-uncoated magnetic Fe₃O₄ nanoparticles could be recycled for 7 times and the ruthenium catalyst supported on silica-coated magnetic Fe₃O₄ nanoparticles could be recycled morethan 14 times.The catalysts could be recovered by external magnetic adsorption,this method is very simple and it could solve the problem of recovery the commercially available Grubbs ruthenium catalyst.