Derivatized cyclodextrins for normal-phase liquid chromatographic separation of enantiomers

Several different derivatized {beta}-cyclodextrins were synthesized and used as chiral stationary phases in normal-phase liquid chromatography. The multiply substituted derivatives were made with acetic anhydride, (R)- and (S)-1-(1-naphthyl)ethyl isocyanate, 2,6-dimethylphenyl isocyanate, and p-toluoyl chloride. The first successful cyclodextrin-based, normal-phase separation of enantiomers was accomplished on these derivative phases. In contrast to chiral separations on the native {beta}-cyclodextrin stationary phase, the enantiomeric separation mechanism on these new phases is not thought to be dependent on inclusion complexation. The similarities and differences between the derivatized cyclodextrin stationary phases and the cellulosic stationary phases are discussed.