PTSA-Catalyzed Chiral Pyrimidine Derivatives: EnantioselectivePreparative HPLC Separation, Configuration, and Greenness Assessment

Introduction: Chiral Dihydropyrimidines (DHPMs) exhibit diverse biological activities depending on their stereochemistry, necessitating efficient enantioselective separation and accurate absolute configuration determination. This research focused on two chiral DHPM derivatives: 4-(3,4- dichlorophenyl)-6-methyl-2-oxo-N-(o-tolyl)-1,2,3,4-tetrahydropyrimidine-5-carboxamide (DHPM-1) and 6-methyl-2-oxo-N-(o-tolyl)-4-(p-tolyl)-1,2,3,4-tetrahydropyrimidine-5-carboxamide (DHPM-2). The study aimed to synthesize these compounds, resolve their enantiomers, determine their absolute configurations, and explore the utility of molecular docking for chiral discrimination, while also assessing the environmental impact of the analytical methods. Methods: Condensation reactions were used to create the target DHPMs. For enantiomeric separation, preparative-scale High-Performance Liquid Chromatography (HPLC) was utilized with Chiral ART Cellulose SC and SZ columns (250 x 30mm, 5μm, 30 mL/min flow rate). Circular Dichroism (CD) and Specific Optical Rotation (SOR) spectroscopy were used to determine the absolute configurations of the separated enantiomers. The potential of this method to differentiate between enantiomers based on their binding to relevant targets was assessed using molecular docking simulations. GAPI and AGREE software were used to evaluate the environmental sustainability of the analytical methods. Results: The enantiomers of DHPM-1 and DHPM-2 were successfully separated by preparative HPLC. The definitive assignment of their absolute configurations was made possible through the analysis of CD spectra and SOR values. Using differences in binding affinities and orientations within the binding pockets, molecular docking simulations successfully distinguished between the enantiomeric pairs. The environmental impact of the analytical processes was thoroughly assessed by the GAPI and AGREE analysis. Discussion: Molecular docking, which reveals stereochemical preferences, is a useful addition to chiral discrimination. The evaluation of analytical methodologies’ greenness directs the creation of ecologically responsible and sustainable actions. Lastly, enantiomerically pure DHPMs can only be obtained using chiral HPLC. Conclusion: This research successfully synthesized and resolved the enantiomers of two chiral DHPM derivatives. The absolute configurations were determined using spectroscopic methods, and molecular docking demonstrated its utility in distinguishing between enantiomers. The environmental evaluation of the analytical methods contributes to the advancement of sustainable chiral analysis. Conclusion: These findings enhance the understanding of asymmetric synthesis and chiral resolution of DHPMs, facilitating the development of novel, stereochemically defined compounds with potential therapeutic applications.