title: High-performance liquid chromatographic separation of dihydropyrimidine racemates on polysaccharide-derived chiral stationary phases.
abstract: The chromatographic behavior of a set of racemic dihydropyrimidines (DHPMs) has been evaluated on two polysaccharide-derived chiral stationary phases under normal phase conditions. One of these is coated, the other chemically immobilized. The outstanding solvent compatibility of the immobilized chiral stationary phase (CSP) permits the use of solvents such as ethyl acetate (EtOAc) that are unsuitable for coated supports, for which traditional 2-propanol:hexanes mixtures have been employed. Drastic changes in the chromatographic retention and resolution of DHPMs and, in general, in the separation performances have been observed for the two systems. From a practical point of view, EtOAc has been proven to be a better choice for the separation of this important class of compounds. By comparing molecules different in specific positions of their scaffolds, hypotheses concerning the role of individual chemical groups on retention and selectivity have been done. These effects have been quantified, in some cases, in terms of standard Gibbs energy variations. Even if no chromatographic measurements have been made under nonlinear conditions, clear indications of the potential use of immobilized chiral adsorptive media operated with EtOAc:hexanes mixtures for preparative separations of DHPMs have been evidenced.
authors.affiliation: Department of Chemistry, University of Ferrara, Via L. Borsari 46, 44100 Ferrara, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Nadalini
authors.forename: Francesco
authors.initials: F
authors.lastname: Dondi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Massi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Dondoni
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.forename: Alberto
authors.initials: A
authors.lastname: Cavazzini
mesh_terms: D000688:Amylose; D002482:Cellulose; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D011744:Pyrimidinones / Q000302:isolation & purification*; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D011744:Pyrimidinones; D002482:Cellulose; D000688:Amylose