LC enantioseparation of β-lactam and β-amino acid stereoisomers and a comparison of macrocyclic glycopepticle- and β-cyclodextrin-based columns

Direct reversed-phase high-performance liquid chromatographic methods were developed for the separation of the enantiomers of tricyclic beta-lactams, cis-3,4-benzo-6-azabi cyclo[3.2.0]heptan-7-one, cis-4,5-benzo-7-azabicyclo[4.2.0] -octan-8-one, cis-5,6-benzo-8-azabicyclo[5.2.0]nonan-9-one and new bicyclic beta-amino acids, the six- and seven-membered komologues of cis-1-amino-4,5-benzocyclopentane-2-carboxylic acid (benzocispentocin), cis-1-amino-5,6-benzocyclohexane-2-carboxylic acid and cis-1-amino-6,7-benzocycloheptane-2-carboxylic acid. The direct separations of the analytes were performed on chiral stationary phase (CSP) columns containing the macrocyclic glycopeptide antibiotic teicoplanin (Chirobiotic T), teicoplanin aglycone (Chirobiotic TAG), vancomycin (Chirobiotic V), vancomycin aglycone (Chirobiotic VAG), ristocetin A (Chirobiotic R) or a new dimethylphenyl carbamate-derivatized beta-cyclodextrin-based Cyclobond DMP. The results achieved with the different methods were compared in systematic chromatographic examinations. The effects of an organic modifier and of the mobile phase composition on the separation and the separation efficiency of different columns were investigated. The difference in enantioselective free energy between the aglycone CSP and the teicoplanin CSP for these beta-lactams and beta-amino acids ranged between 0.3 and -1.1 kJ mol(-1). Better enantioseparations were attained in most cases on the aglycone CSP.