High‐performance liquid chromatographic enantioseparation of amino alcohol analogues possessing 1,2,3,4‐tetrahydroisoquinoline skeleton on polysaccharide‐based chiral stationary phases

Abstract

The stereoisomers of 1,2,3,4-tetrahydroisoquinoline amino alcohol analogues and derivatives thereof were separated in normal-phase mode on chiral stationary phases based on preprepared silica coated with cellulose tris-(3,5-dimethylphenyl carbamate), cellulose tris-(3-chloro-4-methylphenyl carbamate), cellulose tris-(4-methylbenzoate) or cellulose tris-(4-chloro-3-methylphenyl carbamate). On all the investigated chiral columns, the retention and the enantioseparation were influenced by the nature and the concentrations of the mobile phase components and additives, and also the temperature. Experiments were performed in the temperature range 10-50°C. Thermodynamic parameters were calculated from plots of lnα vs 1/T. On these polysaccharide-based chiral columns, both enthalpy-driven separations and entropy-controlled enantioseparations were observed. The latter was advantageous with regard to the shorter retention and greater selectivity at high temperature. The sequence of elution of the stereoisomers was determined in all cases.

Cinchona‐alkaloid‐based zwitterionic chiral stationary phases as potential tools for high‐performance liquid chromatographic enantioseparation of cationic compounds of pharmaceutical relevance

“…From the 1990s, enantioseparation of salsolinol and THIQ analogs was performed by gas chromatography, utilizing indirect liquid chromatography applying isothiocyanatebased chiral derivatizing agent, and by direct LC using ß-CDs and their derivatives as mobile phase additives or selectors incorporated into stationary phases. Related results are collected in a review paper published recently [9]. Besides ß-CDs, selectors based on polysaccharides [9][10][11][12][13], chiral crown ether [14] and, recently, Cinchona alkaloids [13,15] were applied.…”

“…Related results are collected in a review paper published recently [9]. Besides ß-CDs, selectors based on polysaccharides [9][10][11][12][13], chiral crown ether [14] and, recently, Cinchona alkaloids [13,15] were applied. The relatively few direct chromatographic enantioseparations of chiral THβC derivatives were performed on chiral stationary phases based on polysaccharides [12,13,16,17], Cinchona alkaloids [13], and strong cation exchangers (CSPs) [17].…”