Novel tyrosinol-based chiral stationary phase for the separation of tetracyclic quinolines active as PXR agonists: Investigating the enantiorecognition mechanism through molecular dynamics

Background: In recent years, a wide range of chiral molecules has been investigated as potential selectors (SOs) for enantiomeric separation in liquid chromatography, which remains a key tool in the development of new enantiomerically pure pharmaceuticals. SOs encompass diverse chemical and structural classes, from low-molecular-weight molecules to synthetic and biological polymers, many of which are already commercially available. Despite the abundance of commercial chiral stationary phases (CSPs), the demand for novel and more versatile materials remains high. Results: In this study, we present the design and synthesis of a novel tyrosinol-based CSP and its application in separating tetracyclic tetrahydroquinoline derivatives that act as pregnane X receptor agonists. The new CSP demonstrated high enantioselectivity and chemoselectivity under alkane-alcohol (normal-phase) conditions, enabling baseline resolution of all investigated analytes. The enantiomeric elution order (EEO) was unambiguously determined by combining semipreparative-scale chromatography with electronic circular dichroism (ECD) spectroscopy and time-dependent density functional theory calculations. This integrated approach allowed reliable stereochemical assignment of all separated enantiomers and confirmed the consistency of the EEO across the studied series. Complementary molecular dynamics simulations provided mechanistic insight into enantiorecognition, revealing hydrogen bonding as the primary interaction driving enantioselectivity, with π–π and π-cation contacts contributing in a substituent-dependent manner. Significance: Overall, the study highlights the potential of tyrosine-derived selectors as versatile CSPs and demonstrates the added value of combining experimental and computational methods to unravel enantiorecognition mechanisms.