Chiral Resolution through Precipitation of Diastereomeric Capsules in the Form of 2:1 β-Cyclodextrin−Guest Complexes

Preferential precipitation of one enantiomer from a racemic mixture of a camphanate ester of 2,3-diazabicyclo[2.2.2]oct-2-ene was induced by the formation of diasteromeric 2:1 beta-cyclodextrin-guest complexes. The precipitate was enriched with the (-)-enantiomer and the supernatant solution with the (+)-form of a camphanate ester, which was quantitatively analyzed in terms of differential binding constants and intrinsic solubilities of the 2:1 complexes. The enantiomeric excess in the precipitate was determined as 30 +/- 3% by induced circular dichroism.