Separation of 4C-Substituted Pyrrolidin-2-One Derivatives on Amylose-Based Chiral Stationary Phases

Our previous studies concerning the enantioseparation of 4C-substituted pyrrolidin-2-one derivatives on coated polysaccharide-based chiral stationary phases have shown that amylose-based chiral selectors, together with mobile phases consisting of ethanol and n -hexane mixtures, are the most effective. To extend this research, five commercially available immobilized amylose-based chiral stationary phases (3,5-dimethylphenylcarbamate, 3-chlorophenylcarbamate, 3,5-dichlorophenylcarbamate, 3-chloro-4-methylphenylcarbamate and 3-chloro-5-methylphenylcarbamate) were tested with ethanol-containing mobile phases and obtained results were compared with data obtained on coated phases (3,5-dimethylphenylcarbamate and 5-chloro-2-methylphenylcarbamate). The effect of the nature of chiral stationary phase and analytes studied on enantiomer elution order, retention and resolution was tested. Compared to immobilized phase based on amylose 3,5-dimethylphenylcarbamate with its coated version, a better enantioseparation is observed on coated column. However, in addition to the coated amylose-based phases, immobilized phases with both methyl- and chloro-substituents in phenylcarbamate moiety were found to best separate the 4C-substituted pyrrolidin-2-one derivatives. Non-typical eluents with medium-polarity solvents were tested for the separation of three 4C-phenyl-substituted racemic compounds on five immobilized phases. Enantiorecognition of amylose derivatives containing 3,5-dimethylphenylcarbamate and 3-chloro-5-methylphenylcarbamate improved when working with mobile phases containing ethyl acetate, methyl tert- butyl ether and dichloromethane . Graphical abstract