Fomenting proton anisochronicity in the CH2D group

Benjamin D. Allen, Daniel J. O'Leary

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

A novel C-D⋯N interaction promotes an equilibrium isotope effect that causes a large chemical shift difference (43 ppb, 22 °C) for the diastereotopic methyl protons in the (N-CH2D)-(-)-isosparteinium cation. The observed chemical shift difference is in surprising agreement with a prediction of 44 ppb based upon an ab initio protocol. These calculations are also shown to reproduce the experimental shift difference in Anet's α-deutero-1,2-dimethylpiperidine (theory, 17 ppb; experiment, 14 ppb). The isosparteine-derived system described herein may provide an improved method for assigning the configuration and enantiomeric purity of stereogenic methyl groups (R-CHDT) by tritium NMR spectroscopy.

Original languageEnglish (US)
Pages (from-to)9018-9019
Number of pages2
JournalJournal of the American Chemical Society
Volume125
Issue number30
DOIs
StatePublished - Jul 30 2003

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Tritium
Chemical shift
Isotopes
Cations
Protons
Magnetic Resonance Spectroscopy
Nuclear magnetic resonance spectroscopy
Positive ions
Experiments

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

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abstract = "A novel C-D⋯N interaction promotes an equilibrium isotope effect that causes a large chemical shift difference (43 ppb, 22 °C) for the diastereotopic methyl protons in the (N-CH2D)-(-)-isosparteinium cation. The observed chemical shift difference is in surprising agreement with a prediction of 44 ppb based upon an ab initio protocol. These calculations are also shown to reproduce the experimental shift difference in Anet's α-deutero-1,2-dimethylpiperidine (theory, 17 ppb; experiment, 14 ppb). The isosparteine-derived system described herein may provide an improved method for assigning the configuration and enantiomeric purity of stereogenic methyl groups (R-CHDT) by tritium NMR spectroscopy.",
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Fomenting proton anisochronicity in the CH2D group. / Allen, Benjamin D.; O'Leary, Daniel J.

In: Journal of the American Chemical Society, Vol. 125, No. 30, 30.07.2003, p. 9018-9019.

Research output: Contribution to journalArticle

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AB - A novel C-D⋯N interaction promotes an equilibrium isotope effect that causes a large chemical shift difference (43 ppb, 22 °C) for the diastereotopic methyl protons in the (N-CH2D)-(-)-isosparteinium cation. The observed chemical shift difference is in surprising agreement with a prediction of 44 ppb based upon an ab initio protocol. These calculations are also shown to reproduce the experimental shift difference in Anet's α-deutero-1,2-dimethylpiperidine (theory, 17 ppb; experiment, 14 ppb). The isosparteine-derived system described herein may provide an improved method for assigning the configuration and enantiomeric purity of stereogenic methyl groups (R-CHDT) by tritium NMR spectroscopy.

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