Method screening strategies of stereoisomers of compounds with multiple chiral centers and a single chiral center.

Analysis and control of stereoisomers is a major task in pharmaceutical analysis, and is a greater challenge when compounds with multiple chiral centers (MCC) are concerned. HPLC and SFC are commonly used for stereoisomer analysis in drug development, typically starting with chiral method screening. Although method screening for compounds with a single chiral center (SCC) has been well studied for 5-µm polysaccharide stationary phase particles, there are fewer reports on method screening for compounds with MCC and smaller particle sizes. In this study, we systematically evaluated the impact of key parameters in chiral method screening including column particle size (3-µm vs. sub-2 µm), nature of the chiral selector binding (coated vs. immobilized), mobile phase elution mode (isocratic vs. gradient), and separation approach (SFC vs. HPLC). A diverse set of pharmaceutical compounds with MCC and a SCC were studied. We found that the screening strategies differ between MCC and SCC compounds due to the difference in the recognition mechanism involved. Furthermore, we have developed an effective screening strategy with OD-3, AD-3 and IG-3 columns for SCC compounds which achieves larger than 90% success rate, and a combination of OD-3, AD-3, IG-3, IC-3 and AS-3 for MCC compounds which offers the best coverage.