Selectivity enhancement for trans-2-(2,3-anthracenedicarboximido)- cyclohexane-derived diastereomers in HPLC by using an ordered organic stationary phase

2-(2,3-Anthracenedicarboximido)cyclohexane derivatives (AC) have been known as the evolutionary diastereomerizing reagents for enantiomer discrimination in HPLC with ODS. However, a substantial separation of diastereomers can be observed only at lower temperatures, such as -40°C. Therefore, in this work, poly(octadecyl acrylate)-grafted silica, ODA_n was applied as an alternative stationary phase to ODS for the separation of AC-derived diastereomers. As a result, complete separation was achieved even under the conventional condition: for example, methanol as the mobile phase and 0°C as the column temperature. An investigation on the temperature dependency of the selectivity demonstrated that ODA_n shows a remarkable increase in selectivity at temperatures below 30°C, which almost agreed with the peak-top temperature of the endothermic peak in a DSC thermogram for ODA ₃₅ immersed in a mobile phase. The better separation would be derived from a highly ordered structure of ODA_n and a carbonyl-π interaction with AC-derived diastereomers. 2007