R. Tacke et al., THE FIRST LIQUID-CHROMATOGRAPHIC SEPARATION OF THE (R)-ENANTIOMER AND(S)-ENANTIOMER OF A CHIRAL SILANOL, SILANE AND GERMANE, Zeitschrift fur Naturforschung. B, A journal of chemical sciences, 50(4), 1995, pp. 568-572
The racemic mixtures of the muscarinic antagonists cyclohexyl(phenyl)
(2-pyrrolidinoethyl)silanol (sila-procyclidine, rac-1), xyl(hydroxymet
hyl)phenyl(2-piperidinoethyl)-silane (rac-2) and xyl(hydroxymethyl)phe
nyl(2-piperidinoethyl)germane (rac-3) were resolved by analytical liqu
id chromatography (HPLC) using chemically modified cellulose (1) or am
ylose (2, 3) as the chiral stationary phase. This chromatographic meth
od was used for the quantitative determination of enantiomeric purity
of the (R)- and (S)-enantiomers of 1-3, which were obtained by prepara
tive resolution with chiral auxiliary agents. Furthermore, the enantio
meric purity of these samples was established by C-13 NMR studies usin
g chiral shift reagents. According to these studies, the resolved anti
podes of 1-3 (obtained by preparative resolution) were almost enantiom
erically pure [HPLC: greater than or equal to 98.2% ee ((R)-3) to 99.4
% ee ((R)-1, (S)-1); NMR: greater than or equal to 97% ee].