Self-association promoted conformational transition of (3R,4S,8R,9R)-9-[(3, 5-bis(trifluoromethyl)phenyl))-thiourea](9-deoxy)-epi-cinchonine

Péter Király, Tibor Soós, Szilárd Varga, Benedek Vakulya, Gábor Tárkányi

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26 Citations (Scopus)

Abstract

The conformational diversity of the (3R,4S,8R,9R)-9-[(3,5- bis(trifluoromethyl)phenyl))-thiourea](9-deoxy)-epi-cinchonine organocatalyst is discussed. Low-temperature NMR experiments confirmed a self-association process, which promotes the quinoline rotation between two intramolecularly hydrogen-bonded monomeric conformers of the catalyst. The balanced population of the coexisting monomeric and dimeric species allowed us to conduct a structural study of a rather complex conformational dynamics of the pure catalyst. The study is extended by a comparison with other members of the bifunctional amine-thiourea organocatalyst family. Changes in themolecular structure of the catalysts influence the interplaybetween intraand intermolecular hydrogen bonding, and yield different extent of catalyst self-association. By assessing the conformation of the individual states, we established the thermodynamic model of a self-association promoted conformational transition.

Original languageEnglish
Pages (from-to)13-19
Number of pages7
JournalMagnetic Resonance in Chemistry
Volume48
Issue number1
DOIs
Publication statusPublished - Jan 1 2010

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Keywords

  • 2D EXSY
  • CH/pi
  • Conformational analysis
  • Dimer
  • Hydrogen bonding
  • NMR
  • Organocatalysis; chemical exchange
  • Quinoline
  • Self-association

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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