Chiral 2,16-diallyl-, 2,16-dimethyl-, and 2,16-di-tert-butylpyridino-18-crown-6 ligands have been prepared by treating the appropriate chiral α,α′-disubstituted pyridinedimethanol with tetraethylene glycol ditosylate in the presence of base. In these reactions, chiral 2:2 dimers (dipyridino-36-crown-12 derivatives) were also obtained. The log K values for the interaction of these chiral ligands with the enantiomers of (α-phenylethyl)ammonium perchlorate (PhEt) and (α-(1-naphthyl)ethyl)-ammonium perchlorate (NapEt) were measured using an 1H NMR titration method in a CDCl3/ CD3OD (1/1) solvent mixture. The log K values indicate that these chiral pyridino-18-crown-6 ligands have high complexing abilities and some enantiomeric recognition for the chiral organic ammonium perchlorates. The 1H NMR titration experiments also show that the phenyl ring of the guest PhEt is approximately parallel to the pyridine ring in the chiral diallyl- and dimethyl-substituted ligand complexes with chiral PhEt and the phenyl ring is perpendicular to the pyridine ring in the chiral di-tert-butyl-substituted ligand complex with PhEt. These results were supported by MM2 calculations.
|Number of pages||6|
|Journal||Journal of Organic Chemistry|
|Publication status||Published - Nov 29 1996|
ASJC Scopus subject areas
- Organic Chemistry