Kd. Belfield et al., DIRECT DETERMINATION OF ENANTIOMERIC EXCESS OF CARBOCYCLIC ESTERS BY CHIRAL CAPILLARY GAS-CHROMATOGRAPHY, Journal of chromatography, 648(2), 1993, pp. 497-500
Enantiomer separations of monocyclic and bicyclic esters (methyl and e
thyl esters) were carried out directly by capillary gas chromatography
(GC) using a chiral gamma-cyclodextrin fused-silica capillary GC colu
mn. The direct determination of enantioselectivity of an asymmetric al
kylation reaction was achieved. Larger enantiomer separations were fou
nd for the bicyclic esters (alpha = 1.038-1.079) compared to the monoc
yclic esters (alpha = 1.013-1.022). Molecular dimensions, derived from
MM2 energy-minimized structures of a monocyclic ester and a bicyclic
ester, correlate well with thermodynamic data and are consistent with
more than one mechanism of enantio-differentiation.