Deuterium NMR stereochemical analysis of threo–erythro isomers bearing remote stereogenic centres in racemic and non-racemic liquid crystalline solvents
Résumé
We report the proton-decoupled deuterium NMR study of labelled diastereomers with remote stereo-
genic carbons dissolved in various mixtures of poly-gamma-benzyl-l-glutamate (PBLG) and poly-g-benzyl-d-
glutamate (PBDG) liquid crystalline solutions. The evolution of quadrupolar splitting as well as the
diastereomeric and the enantiomeric discrimination versus the proportion of PBLG and PBDG in the
liquid crystalline phase is studied. It is shown that racemic liquid crystalline solutions of PBLG and PBDG
may be used to measure diastereomeric excess (de). Thereafter the spectrum in PBLG solution allows for
measuring the enantiomeric excess (ee) of each diastereomer. These ®rst results suggest substantial
prospects in the ®eld of the analysis of diastereomers with remote stereogenic carbons..