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Remarkably Slow Rotation about a Single Bond between an sp3-Hybridised Carbon Atom and an Aromatic Ring without ortho Substituents

  1. Sarah Murrison1,
  2. David Glowacki Dr.1,
  3. Christian Einzinger Dr.2,
  4. James Titchmarsh1,
  5. Stephen Bartlett Dr.1,
  6. Ben McKeever-Abbas Dr.3,
  7. Stuart Warriner Dr.1,
  8. Adam Nelson Prof.1

Article first published online: 20 JAN 2009

DOI: 10.1002/chem.200802127

Issue

Chemistry - A European Journal

Chemistry - A European Journal

Volume 15, Issue 9, pages 2185–2189, February 16, 2009

Additional Information

How to Cite

Murrison, S., Glowacki, D., Einzinger, C., Titchmarsh, J., Bartlett, S., McKeever-Abbas, B., Warriner, S. and Nelson, A. (2009), Remarkably Slow Rotation about a Single Bond between an sp3-Hybridised Carbon Atom and an Aromatic Ring without ortho Substituents. Chemistry - A European Journal, 15: 2185–2189. doi: 10.1002/chem.200802127

Author Information

  1. 1

    School of Chemistry, University of Leeds, Leeds, LS2 9 JT (UK), Fax: (+44) 113-343-6565

  2. 2

    Institute of Applied Synthetic Chemistry, Getreidemarkt 9/163, 1060 Vienna (Austria)

  3. 3

    AstraZeneca, Hurdsfield Industrial Estate, Macclesfield, SK10 2NA (UK)

Publication History

  1. Issue published online: 6 FEB 2009
  2. Article first published online: 20 JAN 2009
  3. Manuscript Received: 14 OCT 2008

Funded by

  • AstraZeneca
  • EPSRC
  • the University of Leeds
  • the Technical University of Vienna

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Keywords:

  • amides;
  • atropisomerism;
  • electronic structure;
  • multicomponent reactions;
  • polycycles

Graphical Abstract

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Look, noorthosubstituents! A series of polycycles were prepared by using a three-component Joullié–Ugi reaction. The rate of rotation about the bond between a highly hindered bridgehead and a phenyl ring with no ortho substituents was measured, and was highly dependent on the substitution. Rotamer half-lives of up to 21 h at 298 K were observed (see figure). Rotamers resulting from this restricted rotation were isolated for the first time.

Abstract

Look, noorthosubstituents! A series of polycycles were prepared by using a three-component Joullié–Ugi reaction. The rate of rotation about the bond between a highly hindered bridgehead and a phenyl ring with no ortho substituents was measured, and was highly dependent on the substitution. Rotamer half-lives of up to 21 h at 298 K were observed (see figure). Rotamers resulting from this restricted rotation were isolated for the first time.

A series of polycycles was prepared by using a three-component Joullié–Ugi reaction. The rate of rotation about the bond between a highly hindered bridgehead and a phenyl ring with no ortho substituents was measured by using, in general, variable-temperature HPLC. The rate of rotation was highly dependent on substitution and rotamer half-lives of up to 21 h at 298 K were observed. Insights into the effect of substitution on the rate of rotation were gleaned through electronic structure calculations on closely related derivatives. Rotamers resulting from restricted rotation about a bond between an sp3-hybridised carbon atom and a phenyl ring with no ortho substituents were isolated for the first time, and the equilibration of the separated rotamers was followed by using analytical HPLC. It was demonstrated, for the first time, that a highly hindered environment for the sp3-hybridised atom is sufficient for slow bond rotation about a single bond between sp3- and sp2-hybridised carbon atoms.

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