The First Liquid-Chromatographic Separation of the (R)- and (S)-Enantiomers of a Chiral Silanol, Silane and Germane

Abstract

The racemic mixtures of the muscarinic antagonists cyclohexyl(phenyl)(2-pyrrolidinoethyl)silanol (sila-procyclidine, rac-1), cyclohexyl(hydroxymethyl)phenyl(2-piperidinoethyl)silane (rac-2) and cyclohexyl(hydroxymethyl)phenyl(2-piperidinoethyl)germane (rac-3) were resolved by analytical liquid chromatography (H PLC) using chemically modified cellulose (1) or amylose (2, 3) as the chiral stationary phase. This chromatographic method was used for the quantitative determination of enantiomeric purity of the (R )-and (S)-enantiomers of 1 -3 , which were obtained by preparative resolution with chiral auxiliary agents. Further more, the enantiomeric purity o f these samples was established by 13C NM R studies using chiral shift reagents. According to these studies, the resolved antipodes of 1 -3 (obtained by preparative resolution) were almost enantiomerically pure [HPLC: >98.2% ee ((R )-3) to 99.4% ee ((tf)-l, (S )-l); NMR: > 97% ee].

Sila-linalool as a Pheromone Analogue: A Study on C/Si Bioisosterism

“…These findings prompted us to investigate the biological activity of the enantiomers of sila-linalool ( 2b ) . We report here on (i) a new synthesis of rac - 2b , (ii) the gas-chromatographic separation of ( R )- 2b and ( S )- 2b , and (iii) electrophysiological studies with ( R )- 2b and ( S )- 2b using antennae of males of C. cunicularius .

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