Comparison of HPLC enantioseparation of substituted binaphthyls on CD‐, polysaccharide‐ and synthetic polymer‐based chiral stationary phases

Abstract

Retention and enantioseparation behavior of ten 2,2'-disubstituted or 2,3,2'-trisubstituted 1,1'-binaphthyls and 8,3'-disubstituted 1,2'-binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on beta-CD, polysaccharides (tris(3,5-dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans-1,2-diamino-cyclohexane, trans-1,2-diphenylethylenediamine and trans-9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid CSPs). Normal-, reversed-phase and polar-organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non-identical groups and a chiral axis in the 1,2' position had the greatest impact on the enantiomeric discrimination. The 8,3'-disubstituted 1,2'-binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose-based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system.

Recent trends and applications in liquid‐phase chromatography enantioseparation of atropisomers

“…Tesařova and co‐workers described the enantioseparations of ten rac ‐binaphthyls 2 and 65 – 73 (Fig. ) on eight CSPs based on β‐cyclodextrin (Cyclobond I 2000 and Cyclobond I 2000 RPS), polysaccharides (Chiralcel OD‐H, Chiralcel OD‐RH, and Chiralpak AD‐H) and synthetic polymers coated on silica gel (P‐CAP, P‐CAP‐DP, and DEABV; where DEABV is polymer based on bis‐4‐vinylphenylamide monomer of trans ‐9,10‐dihydro‐9,10‐ethanoantracen‐(11 S ,12 S )‐11,12‐dicarboxylic acid; P‐CAP is (1 R ,2 R )‐cyclohexanediyl‐ bis acrylamide polymer; and P‐CAP‐DP is N , N ’‐[(1 R ,2 R )‐1,2‐diphenyl‐1,2‐ethanediyl] bis ‐2‐propenamide polymer) under multimodal elution conditions . These binaphthyl systems are of interest as chiral catalysts with nonidentical groups in the various positions and with a shift of the classical 1,1’‐chiral axis in other positions.…”

Optimization of the surface modification process of cross‐linked polythiol‐coated chiral stationary phases synthesized by a two‐step thiol‐ene click reaction

“…Enantioselective LC using chiral stationary phases (CSPs) has become a workhorse for chiral separations in drug discovery and quality control of enantiomeric drugs as well as many other applications . In general, two distinctly different concepts for the preparation of CSPs have been pursued: brush type CSPs, in which the chiral selectors are covalently linked to the surface (usually silica) by a spacer and polymeric type CSPs with polymeric selectors . Each of the two concepts, brush‐ and polymer‐type CSPs, has its advantages and disadvantages.…”

“…other applications [1,2]. In general, two distinctly different concepts for the preparation of CSPs have been pursued: brush type CSPs, in which the chiral selectors are covalently linked to the surface (usually silica) by a spacer [3][4][5] and polymeric type CSPs with polymeric selectors [6][7][8][9][10][11][12]. Each of the two concepts, brush-and polymer-type CSPs, has its advantages and disadvantages.…”

Separation of atropisomers by chiral liquid chromatography and thermodynamic analysis of separation mechanism

“…The identification of the enantiomer of interest is of great interest to the pharmaceutical community due to the fact that one isomer may have beneficial health properties and the unwanted isomer may have little pharmacological effect, or even show toxicity [1] . Among all the separation techniques used for chiral separation, such as supercritical fluid chromatography (SFC) [2] , [3] , high performance liquid chromatography (HPLC) [4] , gas chromatography (GC) [5] , capillary electrophoresis (CE) [6] , etc. HPLC is the most commonly used technique due to its maturity and wide applications [7] .…”