Enantioseparation using ortho- or meta-substituted phenylcarbamates of amylose as chiral stationary phases for high-performance liquid chromatography

Six ortho- and six meta-substituted phenylcarbamate derivatives of amylose were prepared and their chiral recognition abilities were evaluated as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). The substitution at the meta-position on the aromatic ring was more preferable than that at the ortho-position to obtain CSPs with a high chiral recognition ability, and the introduction of either an electron-withdrawing or electron-donating substituent can improve the chiral resolving power of the meta-substituted phenylcarbamates of amylose. The chiral recognition ability of the amylose phenylcarbamates and elution order of the enantiomers were significantly dependent on the position, nature and number of the substituents on the phenyl group. Correlations between the chiral recognition ability and the N–H frequencies in the IR spectra and the chemical shifts of the N–H protons in the 1H NMR spectra of the carbamate moieties of the amylose derivatives were discussed. The structures of the amylose derivatives were also investigated by circular dichroism spectroscopy.