Stereodynamics of ring and nitrogen inversion in spiroheterocycles. Conformational analysis of N-methylspiro[morpholine-3,2′-adamantane] and N-methylspiro[piperidine-2,2′-adamantane] using NMR spectroscopy and theoretical calculations
Identifieur interne : 001A49 ( Main/Exploration ); précédent : 001A48; suivant : 001A50Stereodynamics of ring and nitrogen inversion in spiroheterocycles. Conformational analysis of N-methylspiro[morpholine-3,2′-adamantane] and N-methylspiro[piperidine-2,2′-adamantane] using NMR spectroscopy and theoretical calculations
Auteurs : Antonios Kolocouris ; Emmanuel Mikros ; Nicolas KolocourisSource :
- Journal of the Chemical Society, Perkin Transactions 2 [ 0300-9580 ] ; 1998.
English descriptors
- Teeft :
- Adamantane, Adamantane derivatives, Adamantane moiety, Adamantane nucleus, Axial, Chax, Chem, Chemical shifts, Cheq, Conformation, Conformational, Conformational changes, Conformer, Conformers, Convergence criterion, Correlation spectra, Correlation spectrum, Derivative, Enantiomeric, Energy barrier, Exchange spectroscopy, Experimental data, Fourier transformation, Heterocycle, Interconversion, Inversion, Kcal, Kolocouris, Magn, Moiety, Molecular mechanics calculations, Morpholine, Nitrogen atom, Nitrogen inversion, Noesy, Noesy spectrum, Pathway, Perkin, Perkin trans, Pharmaceutical chemistry, Piperidine, Proton, Recycling delay, Relative energies, Reson, Ring inversion, Room temperature, Slow interconversion, Steric, Tetrahedron lett, Theoretical calculations, Torsion, Trans, Transition state, Transition states, Variable temperature.
Abstract
Adamantane forces the N-methyl group of N-methylspiro[morpholine-3,2′-adamantane] 1 and N-methylspiro[piperidine-2,2′-adamantane] 2 to adopt an axial orientation and to undergo a slow enantiomerization as depicted by dynamic 1H and 13C NMR spectroscopy. The observed enantiomerization freezes below 0 °C as evidenced by the fully resolved protons and carbons of adamantane in NMR spectra. The observed resonances are interpreted using 2D NMR spectroscopy. Interconversion between the two enantiomeric forms is demonstrated by exchange spectroscopy (EXSY). The activation energy at the coalescence point is calculated from the 13C NMR spectra and found to be 14.3 and 15.2 kcal mol–1 for molecules 1 and 2, respectively. Theoretical calculations suggest a mechanism of interconversion where the significant transition state is the one separating two twist-boat forms.
Url:
DOI: 10.1039/a705868c
Affiliations:
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<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title>Stereodynamics of ring and nitrogen inversion in spiroheterocycles. Conformational analysis of N-methylspiro[morpholine-3,2′-adamantane] and N-methylspiro[piperidine-2,2′-adamantane] using NMR spectroscopy and theoretical calculations</title><author wicri:is="90%"><name sortKey="Kolocouris, Antonios" sort="Kolocouris, Antonios" uniqKey="Kolocouris A" first="Antonios" last="Kolocouris">Antonios Kolocouris</name></author><author wicri:is="90%"><name sortKey="Mikros, Emmanuel" sort="Mikros, Emmanuel" uniqKey="Mikros E" first="Emmanuel" last="Mikros">Emmanuel Mikros</name></author><author wicri:is="90%"><name sortKey="Kolocouris, Nicolas" sort="Kolocouris, Nicolas" uniqKey="Kolocouris N" first="Nicolas" last="Kolocouris">Nicolas Kolocouris</name></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:CB2CDE72D8C3DC9DB4B1BE98F458C220DA8DDEE4</idno><date when="1998" year="1998">1998</date><idno type="doi">10.1039/a705868c</idno><idno type="url">https://api.istex.fr/ark:/67375/QHD-CZKPRGD8-6/fulltext.pdf</idno><idno type="wicri:Area/Istex/Corpus">001184</idno><idno type="wicri:explorRef" wicri:stream="Istex" wicri:step="Corpus" wicri:corpus="ISTEX">001184</idno><idno type="wicri:Area/Istex/Curation">001184</idno><idno type="wicri:Area/Istex/Checkpoint">000844</idno><idno type="wicri:explorRef" wicri:stream="Istex" wicri:step="Checkpoint">000844</idno><idno type="wicri:doubleKey">0300-9580:1998:Kolocouris A:stereodynamics:of:ring</idno><idno type="wicri:Area/Main/Merge">001B04</idno><idno type="wicri:Area/Main/Curation">001A49</idno><idno type="wicri:Area/Main/Exploration">001A49</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a">Stereodynamics of ring and nitrogen inversion in spiroheterocycles. Conformational analysis of N-methylspiro[morpholine-3,2′-adamantane] and N-methylspiro[piperidine-2,2′-adamantane] using NMR spectroscopy and theoretical calculations</title><author wicri:is="90%"><name sortKey="Kolocouris, Antonios" sort="Kolocouris, Antonios" uniqKey="Kolocouris A" first="Antonios" last="Kolocouris">Antonios Kolocouris</name></author><author wicri:is="90%"><name sortKey="Mikros, Emmanuel" sort="Mikros, Emmanuel" uniqKey="Mikros E" first="Emmanuel" last="Mikros">Emmanuel Mikros</name></author><author wicri:is="90%"><name sortKey="Kolocouris, Nicolas" sort="Kolocouris, Nicolas" uniqKey="Kolocouris N" first="Nicolas" last="Kolocouris">Nicolas Kolocouris</name></author></analytic><monogr></monogr><series><title level="j">Journal of the Chemical Society, Perkin Transactions 2</title><title level="j" type="abbrev">J. Chem. Soc., Perkin Trans. 2</title><idno type="ISSN">0300-9580</idno><idno type="eISSN">1364-5471</idno><imprint><publisher>The Royal Society of Chemistry.</publisher><date type="published" when="1998">1998</date><biblScope unit="issue">7</biblScope><biblScope unit="page" from="1701">1701</biblScope><biblScope unit="page" to="1708">1708</biblScope></imprint><idno type="ISSN">0300-9580</idno></series></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0300-9580</idno></seriesStmt></fileDesc><profileDesc><textClass><keywords scheme="Teeft" xml:lang="en"><term>Adamantane</term><term>Adamantane derivatives</term><term>Adamantane moiety</term><term>Adamantane nucleus</term><term>Axial</term><term>Chax</term><term>Chem</term><term>Chemical shifts</term><term>Cheq</term><term>Conformation</term><term>Conformational</term><term>Conformational changes</term><term>Conformer</term><term>Conformers</term><term>Convergence criterion</term><term>Correlation spectra</term><term>Correlation spectrum</term><term>Derivative</term><term>Enantiomeric</term><term>Energy barrier</term><term>Exchange spectroscopy</term><term>Experimental data</term><term>Fourier transformation</term><term>Heterocycle</term><term>Interconversion</term><term>Inversion</term><term>Kcal</term><term>Kolocouris</term><term>Magn</term><term>Moiety</term><term>Molecular mechanics calculations</term><term>Morpholine</term><term>Nitrogen atom</term><term>Nitrogen inversion</term><term>Noesy</term><term>Noesy spectrum</term><term>Pathway</term><term>Perkin</term><term>Perkin trans</term><term>Pharmaceutical chemistry</term><term>Piperidine</term><term>Proton</term><term>Recycling delay</term><term>Relative energies</term><term>Reson</term><term>Ring inversion</term><term>Room temperature</term><term>Slow interconversion</term><term>Steric</term><term>Tetrahedron lett</term><term>Theoretical calculations</term><term>Torsion</term><term>Trans</term><term>Transition state</term><term>Transition states</term><term>Variable temperature</term></keywords></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract">Adamantane forces the N-methyl group of N-methylspiro[morpholine-3,2′-adamantane] 1 and N-methylspiro[piperidine-2,2′-adamantane] 2 to adopt an axial orientation and to undergo a slow enantiomerization as depicted by dynamic 1H and 13C NMR spectroscopy. The observed enantiomerization freezes below 0 °C as evidenced by the fully resolved protons and carbons of adamantane in NMR spectra. The observed resonances are interpreted using 2D NMR spectroscopy. Interconversion between the two enantiomeric forms is demonstrated by exchange spectroscopy (EXSY). The activation energy at the coalescence point is calculated from the 13C NMR spectra and found to be 14.3 and 15.2 kcal mol–1 for molecules 1 and 2, respectively. Theoretical calculations suggest a mechanism of interconversion where the significant transition state is the one separating two twist-boat forms.</div></front></TEI><affiliations><list></list><tree><noCountry><name sortKey="Kolocouris, Antonios" sort="Kolocouris, Antonios" uniqKey="Kolocouris A" first="Antonios" last="Kolocouris">Antonios Kolocouris</name><name sortKey="Kolocouris, Nicolas" sort="Kolocouris, Nicolas" uniqKey="Kolocouris N" first="Nicolas" last="Kolocouris">Nicolas Kolocouris</name><name sortKey="Mikros, Emmanuel" sort="Mikros, Emmanuel" uniqKey="Mikros E" first="Emmanuel" last="Mikros">Emmanuel Mikros</name></noCountry></tree></affiliations></record>Pour manipuler ce document sous Unix (Dilib)
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