139930-23-7Relevant academic research and scientific papers
Effects of substituent and temperature on enantioselectivity for lipase-catalyzed esterification of 2-(4-substituted phenoxy) propionic acids in organic solvents
Watanabe, Keiichi,Koshiba, Takashi,Yasufuku, Yoshitaka,Miyazawa, Toshifumi,Ueji, Shin-Ichi
, p. 65 - 76 (2001)
Substituent effects on the enantioselectivity for the lipase-catalyzed esterifications in organic solvents were studied by use of 2-(4-substituted phenoxy)propionic acids as the substrates with various substituents of H, F, Cl, CF3, CH3, CH3CH2, and CH3O. The distinction in the behavior of their enantioselectivity was primarily responsible for the size effects of the substituents, although the substituents are far away from the stereocenter of the substrates. For the similar substituents in size, CH3 and CF3, however, their electronic effects played an important role in controlling the enantioselectivity. This variation of the enantioselectivity due to the electronic effects is also supported by the discussion based on the value of the Michaelis constant (Km) obtained. In addition, by raising the reaction temperature with enough water added to isopropyl ether as the reaction medium, the enantioselectivity is found to be dramatically enhanced for the substrate bearing CH3O group due to the strong electron-donating effect.
Enantioselective esterification of (RS)-2-(4-chlorophenoxy)propionic acid via Carica papaya lipase in organic solvents
Cheng, Yu-Chi,Tsai, Shau-Wei
, p. 2917 - 2920 (2004)
Carica papaya lipase (CPL) stored in the crude papain is found to be enantioselective for the kinetic resolution of (RS)-2-(4-chlorophenoxy)propionic acid via esterification in anhydrous organic solvents. Of the alcohols screened, trimethylsilylmethanol acted as the best acyl acceptor and gave the highest enzyme activity and enantioselectivity in anhydrous cyclohexane. The kinetic analysis at temperatures between 20 and 60°C indicated that CPL is thermally stable, giving a high E value of 113 at 20°C. A change of cyclohexane to other hydrophobic solvents resulted in better lipase performances. In comparison with the performances of other crude Candida rugosa lipases, Carica papaya lipase is more active, enantioselective and thermally stable.
Metal ions dramatically enhance the enantioselectivity for lipase-catalysed reactions in organic solvents
Okamoto, Takashi,Yasuhito, Ebara,Ueji, Shin-Ichi
, p. 1147 - 1153 (2006)
We propose a simple and a powerful method to enhance the enantioselectivity for lipase-catalysed transformations in organic solvents by an addition of metal ion-containing water to the reaction mixture. In this paper, various metal ions such as LiCl or MgCl2 are tested to improve the enantioselectivity for the model reactions. The enantioselectivities obtained are dramatically enhanced, the E values of which are about 100-fold as compared with the ordinary conditions without a metal ion, for example, E = 200 by addition of LiCl. Furthermore, lowering the reaction temperature led to an almost perfect enantioselectivity of lipase in the presence of a metal ion, for example, E = 1300 by addition of LiCl. Also, a mechanism for the drastic enhancement by metal ions is discussed briefly on the basis of the EPR spectroscopic study and the initial rate for each enantiomer of the substrate. The Royal Society of Chemistry 2006.
Drastic enhancement of the enantioselectivity of lipase-catalysed esterification in organic solvents by the addition of metal ions
Okamoto, Takashi,Ueji, Shinichi
, p. 939 - 940 (1999)
By the addition of metal ion-containing water, a marked enhancement of the enantioselectivity for the lipase-catalysed esterification of 2-(4-substituted-phenoxy)propionic acids in Pr(i)2O was observed, the mechanism of which will be discussed
Lyophilization of lipase together with ionic compounds generates highly enantioselective and solvent-sensitive lipase in organic solvents
Ueji, Shin-Ichi,Mori, Shu-Ichi,Yumoto, Hiromi,Hiroshima, Naomi,Ebara, Yasuhito
, p. 110 - 111 (2005)
The lyophilization of lipase from aqueous enzyme solution containing ionic compounds such as disodium hydrogenphosphate resulted in a dramatic improvement of its enantioselectivity for esterification in organic solvents, compared with the ionic compound-free lipase. The enantioselectivity of the ionic compound-coated lipase was found to be fairly sensitive to the change of the solvents. Copyright
A great improvement of the enantioselectivity of lipase-catalyzed hydrolysis and esterification using co-solvents as an additive
Nishigaki, Tomohiro,Yasufuku, Yoshitaka,Murakami, Sayuri,Ebara, Yasuhito,Ueji, Shin-Ichi
experimental part, p. 617 - 622 (2009/04/11)
Addition of co-solvents such as tetrahydrofuran resulted in a great improvement of the enantioselectivity of lipase-catalyzed hydrolysis of butyl 2-(4-substituted phenoxy)propanoates in an aqueous buffer solution. On the other hand, lipase lyophilized from an aqueous solution containing the co-solvents catalyzed highly enantioselective esterification of 2-(4-substituted phenoxy)propionic acids, 2-(4-isobutylphenyl)propionic acid (ibuprofen), and 2-(6-methoxy-2-naph-thyl)propionic acid (naproxen) in an organic solvent. An increase in the E value up to two orders of magnitude was observed for some substrates. The origin of the enantioselectivity enhancement caused by the co-solvent addition was mainly attributed to a significant deceleration in the initial reaction rate for the incorrectly binding enantiomer, as compared with that for the correctly binding enantiomer. From the results of FT-1R, CD, and ESR spectra, the co-solvent addition was also found to bring about a partial destruction of the tertiary structure of lipase.
Candida Rugosa lipase: Enantioselectivity enhancements in organic solvents
Persichetti, Rose A.,Lalonde, Jim J.,Govardhan, Chandrika P.,Khalaf, Nazer K.,Margolin, Alexey L.
, p. 6507 - 6510 (2007/10/03)
Chiral resolutions of carboxylic acids (1-3) and alcohol (4) were carried out through esterification or transesterification in organic solvents using cross-linked enzyme crystals (CLEC) of Candida rugosa lipase (CRL). Comparison of these results with those of crude CRL reveal significant differences. As was seen in resolution through hydrolysis, a marked improvement in enantioselectivity is realized with the CLEC. Additionally, the stability afforded the enzyme in CLEC form leads to a higher activity in organic solvent.
Quantitative Analyses of Biochemical Kinetic Resolution of Enantiomers. 2. Enzyme-Catalyzed Esterification in Water-Organic Solvent Biphasic Systems
Chen, Ching-Shih,Wu, Shih-Hsiung,Girdaukas, Gary,Sih, Charles J.
, p. 2812 - 2817 (2007/10/02)
New quantitative expressions, which relate the kinetic and thermodynamic parameters that govern the stereospecificity of enzyme-catalyzed resolution of enantiomers in biphasic aqueous-organic media, have been developed.The theoretical predictions have been verified experimentally, and the technical merit of this esterification methodology has been assessed in relation to the more conventional hydrolytic procedure.
