Fast chiral and achiral profiling of compounds with multiple chiral centers by a versatile two-dimensional multicolumn liquid chromatography (LC–mLC) approach

Abstract

It is critical to determine the chiral impurity profile of pharmaceutical compounds. The rising trend of drug candidates bearing multiple chiral centers has aggravated the analytical challenges. The traditional chiral HPLC methods can take gruelingly long time to develop yet may not offer sufficient resolution for all stereoisomers. A fast analytical strategy with a high success rate is in urgent demand for compounds with multiple chiral centers. In this study, we have developed an effective and fast multiple heart-cutting (MHC) multicolumn two-dimensional liquid chromatography (LC–mLC) platform approach. The m in the name of LC-mLC highlights the employment of multiple chiral columns with different chiral selectors and mobile phases in the second dimension (2D) within the same run. A short achiral HPLC method in the first dimension (1D) allows the separation of diastereomers and other achiral impurities, followed by 2D analysis enabling different chiral columns and different mobile phases on each coeluted 1D peak for maximum resolution. This LC–mLC strategy breaks down the complex multiple-chiral-center separation problems into simple individual one-chiral-center separation, which dramatically reduces chiral method development time and sample analysis turnaround. Its versatile nature and fast turnaround approach have made it a highly efficient strategy to enable quick stereoselective synthetic route development. This platform LC–mLC strategy has been successfully demonstrated in separating eight stereoisomers for a pharmaceutical compound with 3 chiral centers, within total method development time of less than 2 hours and a final analysis time of less than 24 min, including column equilibration time. It was also proved highly efficient in separating multiple chiral and achiral components in an in-process sample containing structurally similar starting materials, intermediates, side products and multiple stereoisomers of the product with 3 chiral centers, with minimal method development time.