Investigation of a broadly applicable chiral selector used in enantioselective chromatography (Whelk-O 1) as a chiral solvating agent for NMR determination of enantiomeric composition

A chiral solvating agent (CSA) based on the chiral selector used in the Whelk-O I chiral stationary phase (CSP) was prepared and its scope evaluated. This chiral selector possesses a cleft flanked with aromatic groups and produces upfield chemical shifts for analytes. which are held in this cleft. The enantiomers of each of the Whelk-O I resolvable analytes surveyed show non-equivalent H-1 NMR spectra at room temperature with the addition of only 0.5 equiv of the CSA. Similar non-equivalence is sometimes noted for enantiomers, which do not resolve on this CSP. In such cases, it is apparent that a hydrogen bond acceptor is required and higher CSA to substrate ratios and/or lower temperatures may be needed if adequate resolution of enantiomeric signals is to be obtained. (c) 2005 Elsevier Ltd. All rights reserved.