3976-69-0Relevant articles and documents
Durability enhancement of chirally modified metallic nickel catalysts for enantioselective hydrogenation
Osawa, Tsutomu,Kizawa, Tomoko,Lee, I-Yin Sandy,Ikeda, Shinji,Kitamura, Takayuki,Inoue, Yoshihisa,Borovkov, Victor
, p. 15 - 17 (2011)
Metallic Ni catalysts co-modified with (R,R)-tartaric acid and NaBr showed high enantioselectivity and durability upon hydrogenation of methyl acetoacetate to give methyl 3-hydroxybutyrate. The chirally modified catalyst prepared from 3-μm Ni powder was highly robust to maintain the hydrogenation activity and enantiodifferentiating ability for ca. 3 months under dry condition, which enables long-term storage and hence facilitates commercial distribution and industrial application.
Ligand-acceleration by a chiral modifier in the enantioselective hydrogenation of methyl acetoacetate on a raney nickel catalyst: Effect of a modifier configuration
Sugimura, Takashi,Nakagawa, Satoshi,Kamata, Naoya,Tei, Takahiro,Tajiri, Takashi,Tsukiyama, Ryo-Ichi,Okuyama, Tadashi,Okamoto, Yasuaki
, p. 271 - 276 (2015)
Reaction rate and enantioselectivity of asymmetric hydrogenation of methyl acetoacetate were studied over Raney nickel catalysts modified with (R,R)-tartaric acid, malic acid, or succinic acid to reveal the impacts of the modifier configuration. Catalysts comodified with two different acids were also examined to confirm the conclusions. From analysis of the enantiomer ratio of the hydrogenation product and initial reaction rate, tartaric acid (TA) was found to have dual functions as the modifier during the hydrogenation; effective suppression of the racemic catalysis on bare Ni surface and extensive enantiodifferentiating ligand acceleration by adsorbed TA. It was demonstrated that each adsorbed chiral modifier molecule independently takes part in the enantiospecific hydrogenation.
Highly durable enantio-differentiating nickel catalyst for repeated use for the hydrogenation of methyl acetoacetate
Osawa, Tsutomu,Sakai, Saori,Harada, Tadao,Takayasu, Osamu
, p. 392 - 393 (2001)
The enantio-differentiating hydrogenation of methyl acetoacetate was repeated 30 times over a fine Ni powder catalyst while modifiers (optically active tartaric acid and NaBr) were directly added to the reaction media only in the first run. Over 80% optical yields were attained for the repeated runs. The addition of sodium 2-ethylhexanoate increased the optical yields in the subsequent runs. The very simple and highly durable enantio-differentiating nickel catalyst for repeated use was developed by an in situ modification.
In situ chiral modification of nickel catalysts for enantioselective hydrogenation of methyl acetoacetate
Bartek, Lukas,Kluson, Petr,Cerveny, Libor
, p. 1642 - 1652 (2005)
Chiral modifications of SiO2-supported and Raney nickel catalysts were studied. The catalysts were employed in asymmetric hydrogenation of methyl acetoacetate (MAA) to (R)- and (S)-enantiomers of methyl 3-hydroxybutanoate. The effects of modification parameters such as type and concentration of modifier; presence of a co-modifier and other additives, pH of modification solution on the enantioselectivity of MAA hydrogenation were discussed. Characteristic features of the in situ modification of Ni/SiO 2 were also evaluated and the results obtained were compared with the conventional (premodification) approach. Parameters for the conventional and in situ methods were optimised in a series of experiments for both types of catalysts. The in situ modified Ni/SiO2 was found specifically suitable for repeated use due to virtually no decrease in selectivity and activity.
Enhanced enantioselectivity achieved at low hydrogen pressure for the asymmetric hydrogenation of methyl acetoacetate over a tartaric acid NABR-modified Raney nickel catalyst: A kinetic study
Choliq, Azka Azkiya,Nakae, Rio,Watanabe, Mariko,Misaki, Tomonori,Fujita, Morifumi,Okamoto, Yasuaki,Sugimura, Takashi
, p. 1175 - 1180 (2019)
To ensure high enantiopurity of the product, enantio-differentiating hydrogenation of methyl acetoacetate over a (R,R)-tartaric acid-modified Raney nickel catalyst is normally performed under elevated H2-pressure (310 MPa). In this study, higher enantioselectivity than previously reported for methyl acetoacetate was achieved (92% ee) under low H2pressure of 0.42 MPa. Effects of reaction conditions on the enantioselectivity and hydrogenation rate were investigated using a low-pressure reaction system (2). It was found that impurities in the solvent greatly reduce the enantioselectivity of MAA. The low-pressure reaction system enabled a satisfactory kinetic approach. The reaction rate was well described by Langmuir-Hinshelwood formalism, verifying the previous assumption that the addition of adsorbed hydrogen to the substrate interacting with surface tartrate is a rate-determining step.
The Enantioface-differentiating (Asymmetric) Hydrogenation of the C=O Double Bond with Modified Raney Nickel. XXXVI. The Development of Modified Nickel Catalysts with High Enantioface-differentiating Abilities
Harada, Tadao,Yamamoto, Mihoko,Onaka, Shinji,Imaida, Motomasa,Ozaki, Hiroshi,et al.
, p. 2323 - 2329 (1981)
Various types of modified nickel catalysts were prepared and their enantioface-differentiating (asymmetric) abilities were examined.It was found that the presence of aluminum or related metal compounds in the catalyst was unfavorable for the effective enantioface-differentiating catalyst.The modification with a solution containing tartaric acid and inorganic salt gave a high enantioface-differentiating ability to Raney nickel and reduced nickel catalyst.Among the modified nickel catalysts examined, the Raney nickel modified with tartaric acid and sodium bromide gave the best result with respect to the hydrogenation activity and enantioface-differentiating ability (optical yield 88percent).NaBr adsorbed on Raney nickel was found to inhibit the nonenantioface-differentiating hydrogenation.
Configurationally Fixed α-Alkoxyorganocopper Reagents: 1,4-Addition of Cyclic Enantiopure Transferable Ligands with Complete Retention of Configuration
Lindermann, Russell J.,Griedel, Brian D.
, p. 5491 - 5493 (1991)
Optically active 4-lithio-1,3-dioxanes have been converted to the corresponding TMEDA-organocopper reagents and shown to undergo conjugate addition reactions to ethyl propiolate with complete retention of configuration.
Synthesis and studies of 6,6′-BINAP derivatives for the heterogeneous asymmetric hydrogenation of methyl acetoacetate
Saluzzo, Christine,Lamouille, Thierry,Le Guyader, Frederic,Lemaire, Marc
, p. 1141 - 1146 (2002)
New BINAP derivatives (polyamide, polyureas or ureas) were synthesized and employed in the ruthenium-catalyzed asymmetric heterogeneous hydrogenation of methyl acetoacetate. Enantiomeric excesses in the range 48-100% were observed. Furthermore, the most efficient have been recovered and the recycled catalysts were shown to maintain their efficiency in subsequent reactions.
Catalytic asymmetric hydrogenation of β-ketoesters using new BINAP complexes of ruthenium
Hoke, Jeffrey B.,Hollis, L. Steven,Stern, Eric W.
, p. 193 - 196 (1993)
Two new, air-stable BINAP complexes of ruthenium(II), (RCp)Ru(S-(-)-BINAP)Cl (R = H, CH3) have been prepared in good yield from the reaction of (RCp)Ru(PPh3)2Cl with S-(-)-BINAP in refluxing toluene.The structure of the methylcyclopentadienyl analog has been determined by X-ray crystallography.Both complexes have been found to be effective homogeneous catalysts for the enantioselective hydrogenation of β-ketoesters.
Highly efficient enantio-selective hydrogenation of methyl acetoacetate over an improved tartaric acid-modified raney nickel catalyst
Chen, Hangning,Li, Rong,Wang, Huanling,Yin, Liang,Wang, Fushan,Ma, Jiantai
, p. 910 - 911 (2006)
Using methanol as the reaction medium (an appropriate amount of sodium bromide was directly added to it), the highly efficient enantio-selective hydrogenation of methyl acetoacetate (MAA) was achieved over a tartaric acid-modified Raney nickel catalyst. 85% ee was attained under the comparatively mild conditions (0.6 MPa, 60°C, 1 h). Copyright
