Investigation About Preparation Of Chiral α-Phenylethanolbyacetophenone Using Catalytic Asymmetric Reduction

At present, the modern pharmaceutical industry is developing rapidly, moreand more new drugs have come out, chiral drugs accounts for a substantialproportion. There are three ways to get pure enantiomers of chiral compounds,separation of split method based on the natural products, the synthesis bybio-engineering, and asymmetric catalysis. Asymmetric catalysis appeared laterthan the other methods, but it has been used on a large scale application in theactual industrial production by the rapid development. So catalytic asymmetricsynthesis of enantiomerically pure chiral compounds is high-profile.Chiral α-phenylethanol is important chiral building blocks in Modernorganic synthesis field; it has a wide range of applications in medicine,pesticides and fine chemicals. In this paper, preparation of chiralα-phenylethanol use the method of asymmetric catalysis, acetophenone as rawmaterials,[RuCl₂(p-cymene)₂] as metal catalysts, DPEN ((1R,2R)-1,2-diphenyl ethylenediamine) as the chiral ligand, isopropanol as the source of hydrogen. In a homogeneous environment, the influence factors of the reactionhave been investigated such as: reaction temperature, reaction time, the S/C(ratio of substrate to catalyst), concentration of alkali, the amount of DPEN.Subsequently, this paper synthesized a Anovel chiral ruthenium complexsRuCl[p-cymene][R,R-DPEN]. Using this chiral complexs as an effectivecatalyst, chiral α-benzyl ethanol was prepared through the acetophenoneasymmetric hydrogen transfer reaction. The influence of temperature, time,solvent volume, S/C and alkalinity on reaction conversion and ee value in theasymmetric hydrogen transfer reaction was studied.This paper take MCM-41mesoporous molecular sieves as the carrier,3-chloropropyl triethoxysilane as silane reagent, prepare immobilized catalyst bythe method of grafting. An immobilized catalyst was applied in asymmetryhydrogen transfer reaction of reduction of acetophenone to α-phenylethanol,catalyst could be recovery and reuse. Taking into account the problem ofImmobilization content by the method of grafting, this article prepared hybridSBA-15by copolymerization, and took hybrid SBA-15as carrier immobilizedtransition metal complexes RuCl [p-cymene,][R, the R-DPEN], theperformance of immobilized catalysts were investigated.