Evaluation of a chiral stationary phase derived from a simple Diels‐Alder reaction

Abstract

The bicyclic, C(2)-symmetric dicarboxylic acid obtained from the cycloaddition of fumaric acid to anthracene can readily be prepared in enantiomerically pure form on a large scale. Conversion of either enantiomer of the diacid into its corresponding bis-allylamide yields a selector unit, used as a building block in the synthesis of a chiral stationary phase (CSP). The terminal C-C double bonds in the selector unit were used in a hydrosilylation reaction involving a multifunctional hydrosilane to effect polymerization, crosslinking, and immobilization to the vinyl-silica used as support. A study of the enantiomer-discriminating abilities of the new CSP was made. Large separation factors were obtained for a series of benzodiazepinones, which were studied in further detail by the use of different retention modifiers. To some extent, rationalization of retention data has been achieved in terms of competition for hydrogen bonding.

Evaluation of two pairs of chiral stationary phases: Effects from the length of the achiral spacers

“…As previously shown, the selectivity factors decrease when changing from the protic 2-propanol to the aprotic methyl tert-butyl ether and ethyl acetate, due to the strong hydrogen bonding ability of 2-propanol leading to less contribution from achiral interactions with the sorbent. 5,6 This effect was the same on both the DEABA and the DEABU phases.…”

“…This is particularly apparent from Figure 7a. As an expansion of previous studies, 5 the influence of the length of the achiral spacer on enantioselectivity was studied by chromatography of a series of benzodiazepinones (Scheme 4) on the DEABA and the DEABU phases with mobile phases containing different retention modifiers. Table 3 shows the retention factors and the selectivity factors for the benzodiazepinones 12, 14, 28, and 29 when using mobile phases containing 2-propanol, methyl tert-butyl ether, or ethyl acetate as retention modifiers.…”

“…Mp 127. 5 The hydrogenation catalyst, 10% Pd/C (2.6 g) was added to a mixture of (+)-11 (4.0 g, 9.9 mmol) in ethanol (100 ml) at room temperature. The resulting slurry was stirred under a hydrogen atmosphere at 50jC at 4 atm pressure for 48 h, then cooled to ambient temperature.…”

Copper(I)-BINOL Catalyzed Domino Synthesis of 1,4-Benzoxathiines through -O Bond Formation

“…2-iodothiophenol was prepared by literature procedure [25]. Ligands L2, L3, and L6 were prepared using literature procedure [26][27][28][29][30][31]. Acetonitrile was dried over calcium hydride, freshly distilled, and used for reactions.…”

Investigation of a tartaric acid‐based linear polyamide and dimer as chiral selectors in liquid chromatography

“…The hydrosilylation reaction has been described elsewhere. 13 Surface coverage was determined by elemental analysis (nitrogen: 0.41%), resulting in a molar coverage of 73 mmol/g, which should be compared to that of CHI-DMB (ca. 210 mmol/g).…”