Synthesis Of Imidazolium-tagged Binap Derivatives And Their Application In Asymmetric Hydrogenation

Although asymmetric catalysis is without doubt one of the most promisingmethods for the synthesis of chiral compounds, its industrial applications remain rare,even if a wide variety of reactions have been performed with both highenantioselectivities and conversions. The lack of employment of asymmetric catalysisis partly due to the problems of separation and recovering of the expensive chiralcatalyst. To overcome this drawback, this thesis synthesis BINAP at first, and thenmodified5,5’-positions of BINAP by imidazole to get two new cationic chiraldiphosphine ligand. A catalytic system denoted homogeneous Ionic liquids-MeOHreaction systen was used based on cationic diphosphines ligands, product separationand catalysts recycling was performed by extracting the product from the reactionmixture. This thesis mainly includes:（1） Using （S）-BINOL as the starting material, BINAP was prepared in two steps.Using BINAP as the starting material, modified5,5’-positions of BINAP by imidazoleto get two new cationic chiral diphosphine ligand. The structure of new phosphineligand and precursors were identified by¹H NMR,¹³C NMR and³¹P NMR.（2） Using the model reaction of hydrogenation of methyl acetoacetate, influencesof reaction conditions such as solvent, additives, reaction temperature and pressure onthe catalytic activities and stereoselectivities were examined. The activities andstereoselectivities of recovered phosphine-Ruthenium complex by immobilizationseparation were tested. The results showed that the Ruthenium complexes of these newligands were tested for the asymmetric hydrogenation of methyl acetoacetate in MeOHleading to100%conversion with an enantiomeric excess greater than98%. Inhomogeneous Ionic liquids-MeOH reaction systen, catalysts can be recycled severaltimes by extraction of the product with ether or IPA. Recycling experiments with43asligand, in the case of [BMIM]Tf2N and CH3OH as solvent, catalyst recycle4timesresponse activity and selectivity showed no obvious decline.