Layered Double Hydroxide Nanosheet Modified Chiral Ligand Induced Metal(M = Platinum Or Nickel)Efficiently Catalyzing Asymmetric Hydrogenation Of Ketoesters

Optically active hydroxyester and their derivatives are versatile chiral building blocks for synthesizing many useful fine chemicals and pharmaceuticals.In recent years,the route of the asymmetric hydrogenation of ketoesters to synthesize chiral hydroxyesters,which is proved to be atom-economical and environment-friendly,has been attracted more and more attentions due to its high efficiency.Chiral ligand not only induces the metal active site to establish chirality but reacts with the substrates to produce the hydroxyester.Therefore,the reasonable formation of cyclic intermediate generated by the metal active site,chiral ligand and the substrate is recognized as the key factor to establish efficient catalytic performation.In this paper,layered double hydroxide(LDH)nanosheet modified chiral amino has been employed to induce metal active sites to efficiently catalyze the asymmetric hydrogenation of ketoesters to chiral hydroxyesters.This work focuses on how to utilize LDHs nanosheets to improve the catalytic enantioselectivity as giant rigid substituent of a-amino acids,the basicity of LDH nanosheets to improve the catalytic activity,and confined interlayer space of the intercalated structure to intensify the chemical selectivity.The main reformatory research findings and conclusions are as follows:1.a-Amino acids anions intercalated LDH nanosheets have been used as the chiral ligand to induce Pt nanoparticles to catalyze the asymmetric hydrogenation of EOPB.By employing different amino acids to tailor the interaction with the Pt nanoparticle and EOPB,the conversion and the chemical selectivity have been enhanced.For proline intercalated LDH nanosheet midified Pt nanoparticle exhibits a EOPB conversion of 100%,a chemical selectivity of 84%and an enantioselectivity of 14%of R configuration product.It is found that the simultaneous formation of the Pt-N and Pt-O coordination,and the establishment of N-H…O hydrogen bond or O-H…O are contributed to the improvement of the EOPB conversion and chemical selectivity.2.a-Amino acids anions intercalated LDH nanosheets have been used as the chiral ligand assisted by 1-(1-Naphthyl)ethylamine(NEA)to induce Pt2+to catalyze the asymmetric hydrogenation of EOPB.Pt2+(NEA),(Pro),-Mg2Al1-LDHs exhibits a chemical selectivity of 94%and an enantioselectivity of 247%of S configuration product.It is deduced that the confinement effect plays a crucial role in the improvement on the chemical selectivity and the configuration inversion.3.M-amino acid coordination polymer with helical structure has been intercalated into the LDHs to catalyze the asymmetric hydrogenation of ketoester.Ni(amino acid)2(Py)31D-helix-CPs intercalated LDHs exhibit a EOPB conversion of 58%,a chemical selectivity of 76%and an enantioselectivity of>99%of R configuration product.It is found that the basicity of the LDH nanosheet synergetically improve the conversion and the chemical selectivity.