25140-86-7Relevant articles and documents
Synthesis, characterization, and application of chiral ionic liquids and their polymers in micellar electrokinetic chromatography
Rizvi, Syed Asad Ali,Shamsi, Shahab A.
, p. 7061 - 7069 (2006)
Two amino acid-derived (leucinol and N-methylpyrrolidinol) chiral ionic liquids are synthesized and characterized in both monomeric and polymeric forms. Leucinol-based chiral cationic surfactant is a room-temperature ionic liquid, and pyrrolidinol-based chiral cationic surfactant melts at 30-35 °C to form an ionic liquid (IL). The monomeric and polymeric ILs are thoroughly characterized to determine critical micelle concentration, aggregation number, polarity, optical rotation, and partial specific volume. Herein, we present the first enantioseparation using chiral IL as a pseudostationary phase in capillary electrophoresis. Chiral separation of two acidic analytes, (±)-α- bromophenylacetic acid and (±)-2-(2-chlorophenoxy)propanoic acid (±)-(2-PPA) can be achieved with both monomers and polymers of undecenoxycarbonyl-L-pryrrolidinol bromide (L-UCPB) and undecenoxycarbonyl-L- leucinol bromide (L-UCLB) at 25 mM surfactant concentration using phosphate buffer at pH 7.50. The chiral recognition seems to be facilitated by the extent of interaction of the acidic analytes with the cationic head-group of chiral selectors. Polysodium N-undecenoxycarbonyl-L-leucine sulfate (poly-L-SUCLS) and polysodium N-undecenoxycarbonyl-L-leucinate (poly-L-SUCL) were compared at high and low pH for the enantioseparation of (±)-(2-PPA). AtpH 7.5, poly-L-SUCLS, poly-L-SUCL, and (±)-(2-PPA) are negatively charged resulting in no enantioseparation. However, chiral separation was observed for (±)-(2-PPA) using poly-L-SUCLS at low pH (pH 2.00) at which the analyte is neutral. The comparison of chiral separation of anionic and cationic surfactants demonstrates that the electrostatic interaction between the acidic analyte and cationic micelle plays a profound role in enantioseparation.
(R,S)-2-chlorophenoxyl pyrazolides as novel substrates for improving lipase-catalyzed hydrolytic resolution
Kao, Min-Fang,Lu, Pei-Yu,Kao, Jou-Yan,Wang, Pei-Yun,Wu, An-Chi,Tsai, Shau-Wei
, p. 60 - 66 (2012/05/04)
The best reaction condition of Candida antartica lipase B as biocatalyst, 3-(2-pyridyl)pyrazole as leaving azole, and water-saturated methyl t-butyl ether as reaction medium at 45°C were first selected for performing the hydrolytic resolution of (R,S)-2-(4-chlorophenoxyl) azolides (1-4). In comparison with the kinetic resolution of (R,S)-2-phenylpropionyl 3-(2-pyridyl)pyrazolide or (R,S)-α-methoxyphenylacetyl 3-(2-pyridyl)pyrazolide at the same reaction condition, excellent enantioselectivity with more than two order-of-magnitudes higher activity for each enantiomer was obtained. The resolution was then extended to other (R,S)-3-(2-pyridyl)pyrazolides (5-7) containing 2-chloro, 3-chloro, or 2,4-dichloro substituent, giving good (E > 48) to excellent (E > 100) enantioselectivity. The thermodynamic analysis for 1, 2, and 4-7 demonstrates profound effects of the acyl or leaving moiety on varying enthalpic and entropic contributions to the difference of Gibbs free energies. A thorough kinetic analysis further indicates that on the basis of 6, the excellent enantiomeric ratio for 4 and 7 is due to the higher reactivity of (S)-4 and lower reactivity of (R)-7, respectively.
A new method for production of chiral 2-aryloxypropanoic acids using effective kinetic resolution of racemic 2-aryloxycarboxylic acids
Tengeiji, Atsushi,Nakata, Kenya,Ono, Keisuke,Shiina, Isamu
, p. 1227 - 1252 (2013/08/23)
We report a novel method for the preparation of 2-aryloxypropanoic acids by kinetic resolution of racemic 2-aryloxypropanoic acids using enantioselective esterification. The usage of pivalic anhydride (Piv2O) as an activating agent, bis(a-naphthyl)methanol ((α-Np)2CHOH) as an achiral alcohol, and (+)-benzotetramisole ((+)-BTM) as a chiral acyl-transfer catalyst enables the effective separation of various racemic 2-aryloxypropanoic acids to afford optically active carboxylic acids and the corresponding esters with high enantioselectivities. Furthermore, theoretical calculations of the transition states required to form the chiral esters successfully proved the enantiomer recognition mechanism of the asymmetric esterification.
Optical resolution of aryloxypropionic acids and their esters by HPLC on cellulose tris-3,5-dimethyl-triphenylcarbamate derivative
Azzolina,Collina,Ghislandi
, p. 1401 - 1416 (2007/10/02)
Chiral chromatographic resolution of a series of antiphlogistic 2- aryloxypropionic acids and their methyl and ethyl esters was performed using a Chiralcel OD column. The CSP selected resolved most of the acids and esters efficiently, the enantiomers being well separated without requiring time consuming analysis. Chromatographic separation of R enriched samples was performed to determine the correct elution order. Using eluting systems such as hexane and 2-propanol, or hexane, 2-propanol and formic acid, the S enantiomer of all acids and esters was always found to elute first. We also considered the role of electron-donating or electron-withdrawing substituents (at the aryloxylic moiety) on the chiral resolution. It was shown that the electronic features of the substituents have more influence on the chiral interactions between the solutes and the CSP than their steric hindrance. Finally we determined, by molecular models, the interaction between CSP and solutes. In this way were able to determine all the potential sites for interactions, which are compatible with the conformations of the compounds and the structure of the stationary phase, and point out those interactions which enable chiral resolution.
Enantioselective Hydrolysis of Aryloxypropionic Esters by Bovine Serum Albumin: Enhancement in Selectivity by β-Cyclodextrin
Kamal, Ahmed,Ramalingam, T.,Venugopal, N.
, p. 39 - 42 (2007/10/02)
Bovine serum albumin catalyzed hydrolysis of racemic aryloxypropionic esters affords appreciable enantioselectivity.The effect of β-cyclodextrin this process of hydrolysis has been studied.
Enantioselective inhibition: a strategy for improving the enantioselectivity of biocatalytic systems
Guo,Sih
, p. 6836 - 6841 (2007/10/02)
Dextromethorphan (DM) and levomethorphan (LM) were found to be effective enantioselective inhibitors of Candida cylindracea lipase-catalyzed hydrolysis of a variety of (±)-arlypropionic and (±)-(arloxy)propionic esters. The enantioselectivity of the biocatalytic resolution of (±)-methyl 2-(2,4-dichlorophenoxy)propionate (DCPP) was enhanced 20-fold in the presence of either DM or LM. A general model for enantioselective inhibition has been developed, and a quantitative expression has been derived to show the underlying parameters that govern enantioselective inhibition. To define the mechanism of action of DM, a series of kinetic inhibition experiments was conducted with enantiomerically pure (R)-(+)-DCPP and (S)-(-)-DCPP. The observed inhibition pattern was that of partial noncompetitive inhibition for (R)-(+)-DCPP and that of pure noncompetitive inhibition for (S)-(-)-DCPP.
Enzyme catalysed hydrolysis of chlorophenoxypropionates
Chenevert, Robert,D'Astous, Linda
, p. 1219 - 1222 (2007/10/02)
We report on the enzymatic hydrolysis of methyl 2-phenoxypropionate and of the following chlorinated derivatives: methyl o-chloro-, m-chloro-, p-chloro-, and o,p-dichloro-2-phenoxypropionates. α-Chymotripsyn, lipase, and pig liver esterase have an R enantioselectivity whereas subtilisin has an S enantioselectivity.Enantiomeric excess (e.e.) cover a wide range (from 5 to 100percent).
