Enantioselectivity of lipase‐catalyzed hydrolysis of some 2‐chloroethyl 2‐arylpropanoates studied by chiral reversed‐phase liquid chromatography

Abstract

A technique based exclusively on chiral reversed-phase liquid chromatography has been shown to greatly facilitate studies of enantioselectivity in lipase-catalyzed hydrolysis of chiral organic esters. Only two sets of experimental data are needed to calculate the enantioselectivity (E) of a kinetically controlled enantiomer-differentiating reaction of this kind, viz. the enantiomeric excess of the product (ee,) or substrate (ee,), and the degree of substrate conversion (c). The product enantiomers are well separated on a BSA-based column, giving eep directly. In addition, separation of the (unresolved) ester substrate from the enantiomeric products gives c by integration. Via an optimization of the mobile phase used in the chiral chromatographic system, both these parameters can often be determined in a single run. Highly precise and detailed kinetic studies of the enzymatic reaction can thus be performed. In this way, E-values have been determined for a series of 2-chloroethyl 2-arylpropanoates hydrolyzed in the presence of a Candah cykndracea lipase at pH 6.0 and 7.1. Effects on the E-values from a partial purification and further processing of the lipase have also been studied.

Preparation of S-(+)-ketoprofen by coupling the enantioselective hydrolysis of ketoprofen methyl ester with the photo-oxidation of methanol

“…The surfactant-coated lipase was prepared following the method of Wu et al (2002). Ketoprofen methyl ester was synthesized following the method of Allenmark and Ohlsson (1992). All other chemicals employed in this study were of reagent grade and purchased from Wuhan Chemicals & Reagent Corp., China.…”

An extended model for biochemical kinetic resolution of enantiomers

“…Ketoprofen was obtained from Wuxue Xinda Pharmaceutical Co., Ltd. (China), its optically pure isomers were prepared according to the procedures described by Nohira et al [8]. Ketoprofen methyl ester was synthesised following the method of Allenmark and Ohlsson [9]. All other chemicals employed in this study were of reagent grade and purchased from Wuhan Chemicals & Reagent Corp. (China).…”

Studies of the Heterogeneity of aCandida cylindracea(rugosa) Lipase: Monitoring of Esterolytic Activity and Enantioselectivity by Chiral Liquid Chromatography

“…1. chiral chromatography, provided only that the product enantiomers are well separated from each other and from the substrate (Allenmark and Ohlsson, 1992), E can easily be calculated for any chromatogram recorded during the reaction process. In the assay procedure, where a fixed reaction time is used, c is a rough measure of the enzyme activity present in the isolated fractions.…”

“…Kinetic resolutions via the use of lipases, which preferentially catalyze the hydrolysis and formation of chiral esters and lactones (Gutman et al, 1987;Blanco et al, 1988), often take place with a high degree of enantioselectivity.…”