Recognition by New Symmetrically Substituted Chiral Diphenyl- and Di-tert-butylpyridino-18-crown-6 and Asymmetrically Substituted Chiral Dimethylpyridino-18-crown-6 Ligands of the Enantiomers of Various Organic Ammonium Perchlorates

Peter Huszthy, Jerald S. Bradshaw, Cheng Y. Zhu, Reed M. Izatt, Shneior Lifson, Peter Huszthy

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Abstract

Three new chiral pyridino-18-crown-6 ligands have been prepared. These ligands contain either two phenyl, two tert-butyl, or two methyl substituents on chiral macroring carbon atoms. The chiral di-tert-butyl-substituted diester crown analogue was also prepared. The starting chiral di-tert-butyl-substituted tetraethylene glycol needed to prepare the two di-tert-butyl-substituted crowns was obtained from chiral tert-butyl-1,2-ethanediol, which was resolved from its bis(hydrogen phthalate) brucine salt. A high degree of chiral recognition in CD2Cl2 of the enantiomers of [α-(1-naphthyl)ethyl]ammonium perchlorate (NapEt) was shown by the diphenyl- and di-tert-butyl-substituted crowns as measured by differences in the free energy of activation (ΔGc*) values determined by temperature-dependent *H NMR spectroscopy. The diphenyl- and di-tert-butyl-substituted crowns also exhibited high chiral recognition for the enantiomers of NapEt and other chiral organic ammonium salts in methanol and methanol-chloroform mixtures as shown by a large difference in the log K values determined by a direct NMR technique.

Original languageEnglish
Pages (from-to)3330-3336
Number of pages7
JournalJournal of Organic Chemistry
Volume56
Issue number10
DOIs
Publication statusPublished - May 1 1991

ASJC Scopus subject areas

  • Organic Chemistry

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