CHIRAL HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF ENANTIOMERS OF α-METHYL α-AMINO ACIDS

The enantiomeric separation by chiral high performance liquid chromatography of derivatized and underivatized α-methyl α-amino acids was achieved by two different methods. A cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase column (Daicel Chiralcel OD) was used to resolve N-benzyloxycarbonylated methyl esters. Excellent separations of enantiomers were achieved with all the α-methyl α-amino acids examined. A column packed with octadecylsilanized silica coated with N,S-dioctyl-d-penicillamine as a chiral ligand-exchange phase (Sumichiral OA-5000) was also used to resolve the underivatized amino acids. Excellent to good separations of enantiomers were achieved with a variety of underivatized α-methyl α-amino acids carrying aliphatic or aromatic side-chains by optimizing the amount of the organic component and the concentration of the copper(II) ion in the hydro-organic eluent.