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

Authors

  • Péter Király,

    1. Laboratory for NMR Spectroscopy, Institute of Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59–67, H-1025 Budapest, Hungary
    Search for more papers by this author
  • Tibor Soós,

    1. Department of Synthetic Organic Chemistry, Institute of Biomolecular Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
    Search for more papers by this author
  • Szilárd Varga,

    1. Department of Synthetic Organic Chemistry, Institute of Biomolecular Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
    Search for more papers by this author
  • Benedek Vakulya,

    1. Department of Synthetic Organic Chemistry, Institute of Biomolecular Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
    Search for more papers by this author
  • Gábor Tárkányi

    Corresponding author
    1. Laboratory for NMR Spectroscopy, Institute of Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59–67, H-1025 Budapest, Hungary
    • Laboratory for NMR Spectroscopy, Institute of Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri út 59–67, H-1025 Budapest, Hungary.
    Search for more papers by this author

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 the molecular structure of the catalysts influence the interplay between intra- and 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. Copyright © 2009 John Wiley & Sons, Ltd.

Ancillary