Chae-Sun Baek

Enantiomer Resolution of Nonsteroidal Anti-Inflammatory Drugs on Chiral Stationary Phases Derived from Polysaccharide Derivatives

Abstract The liquid chromatographic enantiomerPDF separation of nonsteroidal anti-inflammatory drugs (NSAIDs) was performed on covalently immobilized chiral stationary phases (CSPs) (Chiralpak IA, Chiralpak IB, and Chiralpak IC) and coated-type CSPs (Chiralpak AD and Chiralcel OD) derived from polysaccharide derivatives. The chromatographic conditions were as follows: the flow rate was 1.0 ml min−1, the detection wavelength was 254 nm, and the standard mobile phase was 2-propanol/hexane/trifluoroacetic acid on all CSPs. A mobile phase of 2-propanol/hexane/trifluoroacetic acid = 10:90:0.1 (v/v) and 2:98:0.1 (v/v) were used on Chiralpak AD and Chiralcel OD of coated-type CSPs, respectively. Several solvents (dichloromethane, tetrahydrofuran, and ethyl acetate) in the mobile phase were used on covalently immobilized CSPs (Chiralpak IA, Chiralpak IB, and Chiralpak IC) and, therefore, solvent versatility of the covalently immobilized CSPs for enantiomer separation of NSAIDs was shown. Also, chromatographic comparisons for enantiomer resolution of these analytes were made on amylose tris (3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak IA and Chiralpak AD) and cellulose tris (3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak IB and Chiralcel OD), respectively. The results indicated that Chiralpak IA and Chiralpak IB showed generally lower enantiomer separation than Chiralpak AD and Chiralcel OD, respectively.

Comparison of several polysaccharide-derived chiral stationary phases for the enantiomer separation ofN-fluorenylmethoxy-carbonyl α-amino acids by hplc

The liquid chromatographic enantiomer separation ofN-fluorenylmethoxycarbonyl (FMOC) protected α-amino acids was performed on nine polysaccharide-derived chiral stationary phases (CSPs). The cellulose derived coated CSPs, Chiralcel OD-H (separation factor = 1.09– 2.70) and Chiralcel OD (separation factor = 1.08–2.55), had the best performance of all the CSPs for resolution ofN-FMOC α-amino acids and therefore, all analyte enantiomers were base-line separated on Chiralcel OD-H and/or Chiralcel OD. Enantioseparation on cellulose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralcel OD-H, Chiralcel OD and Chiralpak IB) is generally greater than that on amylose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak AD-RH, Chiralpak AD and Chiralpak IA). Additionally, coated type CSPs (Chiralcel OD-H or Chiralcel OD, and Chiralpak AD) generally provided better enantioseparation for these analytes than the covalently bonded type CSPs (Chiralpak IB and Chiralpak IA) with the same chiral selector of cellulose tris(3,5-dimethylphenylcarbamate) and amylose tris(3,5-dimethylphenylcarbamate), respectively. However, Chiralpak IB and Chiralpak IA had an advantage over the coated type CSPs in that a broader range of solvents could be used due to its covalently bonded nature.

Lipase mediated chiral resolution of 4-arylthio-2-butanol as an intermediate for β-lactam antibiotics

This paper deals with chiral enzymatic resolution of 4-arylthio-2-butanols by lipase to prepare potential intermediates of β-lactam antibiotics. Among several lipases employed, lipase P type enzyme gave the highest ee value to prepare (R)-4-arylthio-2-butyl acetate. The enzymatic resolution of phenyl substituted alcohol (6a) using lipase P showed the highest ee value (99.7%) among those of 4-arylthio-2-butanol derivatives. Lipase P mediated hydrolysis of acylester7a gave also (R)-alcohol6a selectively. For determination of enantiomeric purity of these enzymatic resolved analytes, liquid chromatographic analysis was performed using two coupled Chiralcel OD and (R,R)-WhelkO chiral column.