Synthesis Of Chiral Diamine Diphosphine Ru Catalysts And Application In The Asymmetric Catalytic Hydrogenation

In this thesis, using (L)-3-(2-Pyridyl)-Alanine as raw materials, the chiral diamine ligands(1a-c,2a-c) were synthesized by two steps:esterification and nucleophilic substitution reaction. The chiral catalysts diamine/diphosphine/Ru (4a-c,5a-c) were prepared by the reaction of [Ru(p-cymene) (S-BINAP)]Cl2(3a) with the diamine ligands (1a-c,2a-c).The chiral catalysts diamine/diphosphine/Ru (4a-c,5a-c) were all soluble in MeOH, EtOH, i-PrOH and CHCl3 with good solubilities. While the second solvent such as petrolem ether, n-hexane, cyclohexane and other nonpolar solvent was added, the catalysts quantitatively precipitated out from the homogeneous phase and then recycled. The structures of chiral catalysts diamine/diphosphine/Ru (4a-c,5a-c) had been characterized by 1H NMR,31P NMR and IR. In the asymmetric hydrogenation reaction of pyruvic acid ethyl ester, the homogeneous catalyst 4c exhibited the best catalytic properties. At the same time, we had investigated the effect of catalytic reaction conditions on the catalytic properties. Under the optimum reaction conditions at 80℃,0.5 h, 40 atm H2,i-PrOH (15 mL), molar ratio of pyruvic acid ethyl ester/catalyst/PTSA=100:1:20, catalyst 4c gave 94.8% yield and 67.4%ee. After the reaction was completed, the second nonpolar solvent was added, the homogeneous catalysts 4a-c and 5a-c can be precipitated out and recovered by the centrifugation or filtration, and reused without the sharp loss of catalytic activities for four times.