Enantiomeric Separation of Racemic 4‐Aryl‐1,4‐Dihydropyridines and 4‐Aryl‐1,2,3,4‐Tetrahydropyrimidines on a Chiral Tetraproline Stationary Phase

The chromatographic chiral resolution of 4‐aryl‐1,4‐dihydropyridines ( 1–32 ), 4‐aryl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidines ( 33–38 ), and 4‐aryl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidines ( 39–41 ) was studied on a tetraproline‐immobilized chiral column synthesized in our lab. This tetraproline chiral stationary phase can resolve most of these compounds. The 4‐aryl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidines ( 33–38 ) and 4‐aryl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidines ( 39–41 ) were more efficiently resolved than the racemic 4‐aryl‐1,4‐dihydropyridines on the tetraproline chiralstationary phase. Analytes with 5,5‐dimethyl groups ( 39–41 ) were less efficiently resolved than analytes without 5,5‐dimethyl substituents ( 1–16 ). The 4‐aryl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidines ( 39–41 ) without a sulfur atom were much more efficiently resolved than 4‐aryl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidines ( 33–38 ). No obvious electronic effects on the resolution of any of these analytes ( 1–41 ) were observed on the tetraproline chiral stationary phase. The tetraproline chiral stationary phase separated enantiomers mainly via hydrogen bonding interactions. Chirality, 2013. © 2013 Wiley Periodicals, Inc.