110171-06-7Relevant academic research and scientific papers
Asymmetric visible-light photobiocatalytic reduction of β-keto esters utilizing the cofactor recycling system in Synechocystis sp. PCC 6803
Tanaka, Shusei,Kojima, Hideo,Takeda, Satomi,Yamanaka, Rio,Takemura, Tetsuo
, (2020)
The asymmetric reduction of β-keto esters employing a wild-type strain of cyanobacterium Synechocystis sp. PCC 6803 under illumination of red LED light at 25 °C for 24 h was evaluated. As a result, the corresponding (R)-β-hydroxy esters were obtained as major products. The R-selectivity was shown to increase for bulkier substrates. Moreover, it was also found that the R-selectivity increased with decreasing substrate concentrations. This can be explained by the assumption that the Km value of the R-selective reductase is smaller than that of the S-selective enzyme involved in the reaction. Additionally, it was demonstrated that the R-selective reductase required the light-dependent production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) for effective reaction; however, the S-selective variant did not. Overall, cyanobacterium was employed as a sustainable photobiocatalyst proliferating under illumination of light, while utilizing inorganic salts and atmospheric carbon dioxide (CO2). Employing the whole-cell system allowed for the preparation of industrially-important chiral compounds, such as optically active β-hydroxy esters.
Ruthenium catalyzed asymmetric hydrogenation of α- and β-keto esters in ionic liquids using chiral P-Phos ligand
Lam, Kim Hung,Xu, Lijin,Feng, Lichun,Ruan, Jiwu,Fan, Qinghua,Chan, Albert S.C.
, p. 903 - 908 (2005)
Chiral dipyridylphosphine ligand P-Phos was used in the Ru catalyzed asymmetric hydrogenation of α- and β-keto esters in room temperature ionic liquids (RTILs) with high conversions and good to excellent enantioselectivities. The catalyst was recycled by simple extraction and reused five times without loss of activity and enantioselectivity.
Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β-Keto Esters
Hu, Aiguo,Ngo, Helen L.,Lin, Wenbin
, p. 6000 - 6003 (2003)
Catalytic building blocks: Chiral porous zirconium phosphonates containing Rubinap moieties are synthesized by a molecular building-block approach, and characterized by a variety of techniques. These hybrid solids are used for enantioselective heterogeneous asymmetric hydrogenation of β-keto esters with ee values of up to 95% (see picture). Ready tunability of such a molecular building-block approach promises to lead to useful heterogeneous asymmetric catalysts.
Chirally functionalized mesoporous organosilicas with built-in BINAP ligand for asymmetric catalysis
Wang, Peiyuan,Liu, Xiao,Yang, Jie,Yang, Yan,Zhang, Lei,Yang, Qihua,Li, Can
, p. 8009 - 8014 (2009)
The chirally functionalized periodic mesoporous organosilica (PMO) with C2-symmetric chiral building blocks, BINAP (2,2′- bis(diphenylphosphino)-1,1′-binaphthyl), in the pore wall was successfully synthesized for the first time using a successive co-condensation and post-synthesis modification method. Chiral BINAPO (2,2′- bis(diphenylphosphinooxide)-1,1′-binaphthyl) bridging mesoporous organosilica with highly ordered 2-D hexagonal structure was first synthesized by co-condensation of (R)-5,5′-bis(3-triethoxysilylpropyl-1-ureyl)-2, 2′-bis(diphenylphosphinooxide)-1,1′-binaphthy with tetramethoxylsilane in the presence of block copolymer P123 as template under weakly acidic conditions. The BINAPO in the pore wall of PMO was reduced with trichlorosilane to generate BINAP using a post-synthesis modification method. The chiral PMO with built-in BINAP (coordination with [RuCl2- (benzene)]2) is an efficient solid catalyst for the asymmetric hydrogenation of β-keto esters with ee as high as 99%, which is among the highest ever reported for the chirally functionalized PMOs in asymmetric catalysis.
General Stereodivergent Enantioselective Total Synthetic Approach toward Macrosphelides A-G and M
H?cker, Christine,Plietker, Bernd
, p. 8055 - 8064 (2015)
A straightforward enantioselective total synthesis algorithm for the preparation of 8 out of 13 macrosphelides within 9-11 steps starting from tert-butyl sorbate is presented. The use of a cyclic sulfate as both protecting and reactivity directing group is the key element within this algorithm. A high-pressure transesterification allows for the selective ring-enlargement of the 15-membered macrosphelides into the 16-membered counterparts. The absolute configurations of the natural products were unambiguously assigned both by the chemical synthesis and by X-ray structure analysis.
Ruthenium(II)-Catalyzed Asymmetric Transfer Hydrogenation of Carbonyl Compounds with 2-Propanol and Ephedrine-Type Ligands
Everacre, Kathelyne,Mortreux, André,Carpentier, Jean-Fran?ois
, p. 67 - 77 (2003)
This account describes the development and application of Noyori's type catalysts based on ruthenium-arene complexes and simple chiral β-amino alcohols derived from ephedrine, for the asymmetric transfer hydrogenation of 2-propanol to carbonyl substrates. The influence of key parameters of the catalyst system has been studied systematically, resulting in particular in the design of the novel ligand (4-biphenylmethyl)norephedrine. Thanks to the latter, the catalytic precursors and true active species could be isolated for the first time, enabling a complete structural description of the catalytic cycle and of probable deactivation pathways. Highly effective applications of those catalysts systems, i.e., the asymmetric reductions of simple aryl ketones and aryl β-keto esters, the synthesis of chiral phthalides and syn-β,δ-dihydroxy esters, are described.
Effect of organic solvents on asymmetric reduction of β-keto esters using cyanobacterium Synechocystis sp. PCC 6803
Tanaka, Shusei,Kojima, Hideo,Takeda, Satomi,Yamanaka, Rio,Takemura, Tetsuo
, (2021)
The asymmetric reduction of tert-butyl 3-oxobutanoate by cyanobacterium Synechocystis sp. PCC 6803 under illumination with red LED light at 25 °C for 24 h afforded the corresponding (R)-β-hydroxy ester in 79% enantiomeric excess (ee) (81% yield), while the addition of toluene (1% (v/v)) to the system gave the corresponding (S)-β-hydroxy ester in >99% ee (87% yield). Organic solvents such as chloroform, benzene, ethylbenzene, cyclohexane, and methylcyclohexane showed similar effects and afforded the corresponding (S)-β-hydroxy ester in >99% ee. However, polar organic solvents, such as DMSO, THF, and ethanol, as well as dodecane—a hydrophobic solvent with a straight long-chain—did not exhibit such effects.
An Improved Procedure for the Synthesis and Use of 2*NEt3. Dependence of the Ru(II)-BINAP Catalyzed Asymmetric Hydrogenation of β-Keto Esters on Trace Amounts of Acid
King, Steven A.,Thompson, Andrew S.,King, Anthony O.,Verhoeven, Thomas R.
, p. 6689 - 6691 (1992)
The asymmetric hydrogenation of β-keto esters using 0.02-0.05 mol percent Ru(II)-BINAP-derived catalyst can be conducted in a standard Parr shaker apparatus at 40 deg C and 30 psi of hydrogen in the presence of 0.1 mol percent of a strong acid.
Enhanced enantioselectivity in the heterogeneous catalytic hydrogenation of acetoacetate esters into the corresponding 3-hydroxybutyrates using commercial nickel powder
Osawa, Tsutomu,Kizawa, Tomoko,Ikeda, Shinji,Kitamura, Takayuki,Inoue, Yoshihisa,Borovkov, Victor
, p. 1630 - 1633 (2014)
Heterogeneous catalytic hydrogenation of acetoacetic acid esters over tartaric acid/NaBr-modified Ni powder was determined to be a critical function of the steric bulk of the ester moiety to afford quantitatively 3-hydroxybutyrate in 94% enantiomeric excess when ethyl and i-butyl esters are used, providing a facile route to optically active 3-hydroxybutyrates.
Whole cells in enantioselective reduction of tert-butyl acetoacetate
De Souza Ramos, Aline,Ribeiro, Joyce Benzaquem,De Oliveira Lopes, Raquel,De Souza, Rodrigo Octavio Mendonca Alves
, p. 1611 - 1618 (2013)
The b-ketoester tert-butyl acetoacetate was enantioselectively reduced to tertbutyl (S)-3-hydroxybutanoate by seven microorganism strains. The best result using free cells was obtained with the yeast R. rubra, which furnished 97.6% ee and higher than 99% of conversion within 24 h. After immobilization in calcium alginate spheres, R. rubra furnished 96% ee and higher than 99% ee within 24 h, even if substrate concentration was 58mM. Immobilized cells were reused three times without loss of enantioselectivity. Copyright Taylor & Francis Group, LLC.
