Application of selective F1 decoupled 1H NMR for enantiomer resolution and accurate measurement of enantiomeric excess at low chiral substrate/auxiliary concentration

摘要

The higher substrate and chiral auxiliary concentration is a pre-requisite to obtain efficient separation of 1H NMR signals of enantiomers. The higher concentration of chiral lanthanide shift reagents provides broadened spectral lines resulting in a severe loss of resolution between the enantiomer resonances. In order to circumvent such difficulties, herein we present the application and the usefulness of a selective F1 decoupled correlation (COSY) experiment which yields proton decoupled proton spectra in the indirect dimension. The potentiality of the experiment is demonstrated on several chiral compounds possessing different functional groups, employing either a lanthanide shift reagent or a solvating reagent as chiral auxiliaries.