(l)- or (d)-Valine tert-butylamide grafted on permethylated β-cyclodextrin derivatives as new mixed binary chiral selectors

Gas chromatographic enantioseparation of derivatized α-amino acids on chiral stationary phases—Past and present

“…Courtesy, Prof. U.Meierhenrich. gle l-valine diamide moiety in the C6-position of permethylated ␤-cyclodextrin for enantioseparations by GC[99].…”

An alternative scheme for the multiplexed acquisition of 1D and 2D NMR spectra

“…1 shows the structure of compound 1, its 500 MHz 1 H NMR spectrum and an expansion of the anomeric protons. Our interest in this molecule came from its use in the synthesis of new efficient stationary phases for gas chromatographic applications [12]. The seven sugar spin systems were labeled A-G, according to the order of appearance of their anomeric protons.…”

Separation of Enantiomers by Gas Chromatography on Chiral Stationary Phases

“…The selector Valdex (heptakis[6-O-(N -acetylyl-l-valine-tertbutylamide)-2,3-O-methyl]-β-cyclodextrin) represents a versatile chiral solvating agent (CSA) for the NMR spectroscopic discrimination of enantiomers which associate either with the permethylated cyclodextrin selector (e.g., for apolar trisubstituted allenes) or with the diamide selector (e.g., for polar 2-alkyl-α-amino acid derivatives) [164], but no remarkable enantioseparations of different classes of compounds were observed on Chirasil-Valdex in the GC mode. However, promising results have been obtained on a selector that carries only a single l-valine diamide moiety in the C6-position of permethylated β-cyclodextrin for enantioseparations by GC [165].…”