18221-58-4Relevant academic research and scientific papers
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.
Chiral resolution of methyl 2-aryloxypropionates by biocatalytic stereospecific hydrolysis
Azzolina,Vercesi,Collina,Ghislandi
, p. 221 - 226 (2007/10/02)
The hydrolysis of 2-aryloxypropionyl methyl esters by α-chymotrypsin, lipase P and carboxylesterase NP was carried out to perform chiral resolution of their racemates. The biocatalytic activity of carboxylesterase NP was undoubtedly higher than that of the other enzymes: in fact the reaction rate was greater and the enantioselectivity values were better even though less amount of enzyme was employed. This enzyme was thus the most suitable to catalyze the enantiospecific hydrolysis of the tested compounds in aqueous media. The reaction was also attempted in organic solvents. The evaluation of the produced acid and the unreacted ester was accomplished by chiral HPLC on Chiralcel OD, OD-H and Chiralpak AD columns. In general the configuration of the preferentially hydrolyzed enantiomer was S, but for all the compounds having an alkyl substituent (methyl or ethyl) on the 2 position of the aromatic ring the enantioselectivity of the enzymatic conversion was reverse. When compared, there did not appear to be any particular relationship between conversion, enantioselectivity data and chemical features (size or position of the substituents on the aromatic ring).
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.
