139930-23-7Relevant articles and documents
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.
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.
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
