Synthesis and characterisation of medium-sized ring systems by oxidative cleavage. Part 2: Insights from the study of ring expanded analogues

Tomas Lebl*, Magali M. Lorion, Alan M. Jones, Douglas Philp, Nicholas J. Westwood

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Variable temperature NMR analysis and computational methods have been used to develop a detailed understanding of the 1H NMR spectra of a family of medium-sized ring containing compounds. The family consists of analogues containing 10-, 11- and 12-membered rings and in all cases the NMR spectra at room temperature showed a series of diastereotopic methylene signals despite the lack of a stereogenic centre in these systems. On repeating the NMR analysis at higher temperatures, all the signals coalesced for the 12-membered ring system consistent with full interconversion of ring conformers. This was not observed in the analogous 10- and 11-membered ring systems with the interchange of conformers remaining slow on the NMR timescale. However, 1D gs-NOESY/EXSY NMR experiments showed that in the smaller ring systems interconversion of diastereotopic protons did occur. Computational studies suggest that the dynamic process observed by NMR for the 10- and 11-membered rings systems is different from that observed in the 12-membered ring containing compound.

Original languageEnglish (US)
Pages (from-to)9694-9702
Number of pages9
JournalTetrahedron
Volume66
Issue number51
DOIs
StatePublished - Dec 18 2010

Keywords

  • Heterocycle
  • Mechanism
  • Medium-sized ring
  • Oxidative fragmentation
  • VT NMR analysis

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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