Asymmetric hydrogenation of acetylace tonates on raney nickel catalyst

Клабуновский, Е. И.; Соколова, Н. П.; Petrov, Yu. I.; Patrikeev, V. V.; Neupokoev, V. I.; Рубцов, И. А.

doi:10.1007/bf00953472

Cited by 2 publications

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“…Only much later, in the early 1960s, were promising ee’s obtained by Izumi and co-workers who used tartaric acid, which proved to be an effective chiral modifier in the hydrogenation of β-ketoesters . Many variations with respect to catalyst preparation, additives, solvents, ambient pressure, and substrate hydrogenation have been explored, and these are well documented elsewhere. , Metals other than Ni have also been investigated but were found to be significantly less effective . The lack of correlation between the kinetic behavior and ee has been interpreted to suggest that only some areas of the hydrogenated catalyst surface lead to enantiodifferentiation .…”

Section: Introductionmentioning

confidence: 99%

Aspects of Heterogeneous Enantioselective Catalysis by Metals

2011

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Publisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Langmuir, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://pubs.acs.org/doi/abs/10.1021/la200009w. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Some aspects of metal-catalyzed heterogeneous enantioselective reactions are reviewed with specific 23 reference to four different systems where the phenomena that control enantioselection appear to be very 24 different. In the case of glucose electro-oxidation it is clear that any intrinsic chirality present at the 25 metal surface plays a vital role. With -keto hydrogenation, achiral surfaces modified by the adsorption 26 of chiral agents become effective enantioselective catalysts and formation of extended arrays of chiral 27 species appears not to be of importance: instead a 1:1 docking interaction controlled by hydrogen 28 bonding between the adsorbed chiral modifier and the prochiral reactant determines the outcome. 29Hydrogen bonding also plays a central role in -ketoester hydrogenation, but here fundamental studies 30indicate that the formation of ordered arrays involving the reactant and chiral ligand is of importance. 31Asymmetric C=C hydrogenation, though relatively little studied, has the potential for major impact in 32 synthetic organic chemistry both at the laboratory scale and in the manufacture of fine chemicals and 33 pharmaceuticals. The structural attributes that determine whether or not a given chiral ligand is effective 34 have been identified; the ability to form strong covalent bonds with the metal surface while also 35 resisting hydrogenation and displacement by the strongly-adsorbing reactant under reaction conditions 36 are essential necessary conditions. Beyond these, ligand rigidity in the vicinity of the chirality center 37 coupled with resistance to SAM formation are critically important factors whose absence results in 38 racemic chemistry.

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Section: Introductionmentioning

confidence: 99%

Aspects of Heterogeneous Enantioselective Catalysis by Metals

2011

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“…, using TA modified Raney nickel, have reported steady progress in improving enantioselectivity from 3−5% in 1956 to > 80% in 1981 . The reported dependence of selectivity on reaction variables is conflicting in that, for instance, (a) maxima have been quoted at reaction temperatures of 323 K, , 328−333 K, and 343−353 K, , (b) temperature independence has been observed in the range 333−393 K, and (c) selectivity was shown to decrease as the temperature was raised from 323 to 353 K …”

Section: Introductionmentioning

confidence: 99%

Interaction of Optically Active Tartaric Acid with a Nickel−Silica Catalyst: Role of Both the Modification and Reaction Media in Determining Enantioselectivity

Keane

1997

Langmuir

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An enantioselective Ni/SiO2 catalyst has been prepared by modification with aqueous, methanolic, ethanolic, and butanolic solutions of (R)-(+)-tartaric acid (TA) and used in the asymmetric hydrogenation of a prochiral β-keto ester (methyl acetoacetate) to a β-hydroxy ester ((R)-(-)-methyl 3-hydroxybutyrate). The effects of systematically varying the modification time and temperature, modifier concentration, and the incorporation of NaBr as a comodifier on the uptake of TA and on the ultimate activity and enantioselectivity are discussed. The nature of the interaction of TA with the surface nickel metal is considered and data on the corrosive leaching of nickel from the catalyst surface are presented. The degree of TA adsorption was found to increase and the extent of nickel dissolution to decrease with the following sequence of modifier solvents: water, methanol, ethanol, 1-butanol. Changes in hydrogenation activity and enantioselectivity are reported as a function of the reaction time, temperature, and the reactant to catalyst molar ratio. Modification of the catalyst with TA not only induced enantioselectivity but also promoted the rate of hydrogenation where the alcoholic treatments yielded the highest activities and selectivities. The reaction exhibits typical Langmuir-Hinshelwood behavior and reaction orders with respect to methylacetoacetate and hydrogen concentrations and apparent activation energies are provided. The effect of the reaction solvent on product composition is discussed, and a linear relationship between the apparent rate and dielectric constant of the reaction medium, in the case of alcoholic solvents, is presented. The action of thiophene, acetic acid, and water as additives is identified, and catalyst durability is addressed.

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Asymmetric hydrogenation of acetylace tonates on raney nickel catalyst

Cited by 2 publications

References 2 publications

Aspects of Heterogeneous Enantioselective Catalysis by Metals

Aspects of Heterogeneous Enantioselective Catalysis by Metals

Interaction of Optically Active Tartaric Acid with a Nickel−Silica Catalyst: Role of Both the Modification and Reaction Media in Determining Enantioselectivity

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