The effects of aromatic substituents on the chromatographic enantioseparation of diarylmethyl esters with the Whelk-Ol chiral stationary phase

Members of a series of diarylmethanols, diarylmethyl pivalates, and diarylmethyl acetates (analyte sets 1-26) were enantio-resolved with the (S,S)-Whelk-O1 chiral stationary phase (CSP). An analogue of the (S,S)-Whelk-O1 selector was combined with enantioenriched samples of the various diarylmethyl pivalates and thereby used as a chiral solvating agent (CSA) for high field H-1 NMR studies. The absolute configurations of a number of chiral diarylmethyl pivalates were assigned using this approach, and hydrolysis of the pivalates allowed assignment of the absolute configurations of the corresponding diarylmethanols. Chromatographic, H-1 NMR, and X-ray evidence are given in support of a chiral recognition model for the enantioresolution of diarylmethyl esters on this CSP. (C) 2004 Elsevier B.V. All rights reserved.