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Stereostructure Assignment of Flexible Five-Membered Rings by GIAO 13C NMR Calculations: Prediction of the Stereochemistry of Elatenyne.

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Title: Stereostructure Assignment of Flexible Five-Membered Rings by GIAO 13C NMR Calculations: Prediction of the Stereochemistry of Elatenyne.
Authors: Smith, Steven G.1, Paton, Robert S.1, Burton, Jonathan W.2 jonathan.burton@cheni.ox.ac.uk, Goodman, Jonathan M.1 j.m.goodtnan@ch.carn.ac.uk
Source: Journal of Organic Chemistry. 6/6/2008, Vol. 73 Issue 11, p4053-4062. 10p. 5 Diagrams, 4 Charts, 10 Graphs.
Subjects: Stereochemistry, Chemical structure, Conformational analysis, Chemical reactions, Nuclear isomers
Abstract: The stereochemistry of conformationally mobile five-membered rings is often hard to assign from NMR data, and [2,2′]bifuranyl systems are even more challenging. GIAO 13C NMR chemical shifts have been calculated for a series of [2,2′]bifuranyl and pyranopyran species, taking into account their conformational flexibility using weighted averages of the data for all low energy conformers. We show that calculation of 13C NMR chemical shifts using the geometries obtained using molecular mechanics greatly reduces the computational expense without a significant loss of accuracy, even in this demanding system. The results were sufficiently accurate to distinguish not only the pyran and furanyl isomers but also between all the diastereoisomeric forms. As a result of this validation, we predict the stereochemistry for the recently proposed revised structure of the natural product elatenyne, which contains a [2,2′]bifuranyl core. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Organic Chemistry is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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  Data: Stereostructure Assignment of Flexible Five-Membered Rings by GIAO <superscript>13</superscript>C NMR Calculations: Prediction of the Stereochemistry of Elatenyne.
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Organic+Chemistry%22">Journal of Organic Chemistry</searchLink>. 6/6/2008, Vol. 73 Issue 11, p4053-4062. 10p. 5 Diagrams, 4 Charts, 10 Graphs.
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  Data: <searchLink fieldCode="DE" term="%22Stereochemistry%22">Stereochemistry</searchLink><br /><searchLink fieldCode="DE" term="%22Chemical+structure%22">Chemical structure</searchLink><br /><searchLink fieldCode="DE" term="%22Conformational+analysis%22">Conformational analysis</searchLink><br /><searchLink fieldCode="DE" term="%22Chemical+reactions%22">Chemical reactions</searchLink><br /><searchLink fieldCode="DE" term="%22Nuclear+isomers%22">Nuclear isomers</searchLink>
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  Data: The stereochemistry of conformationally mobile five-membered rings is often hard to assign from NMR data, and [2,2′]bifuranyl systems are even more challenging. GIAO 13C NMR chemical shifts have been calculated for a series of [2,2′]bifuranyl and pyranopyran species, taking into account their conformational flexibility using weighted averages of the data for all low energy conformers. We show that calculation of 13C NMR chemical shifts using the geometries obtained using molecular mechanics greatly reduces the computational expense without a significant loss of accuracy, even in this demanding system. The results were sufficiently accurate to distinguish not only the pyran and furanyl isomers but also between all the diastereoisomeric forms. As a result of this validation, we predict the stereochemistry for the recently proposed revised structure of the natural product elatenyne, which contains a [2,2′]bifuranyl core. [ABSTRACT FROM AUTHOR]
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  Data: <i>Copyright of Journal of Organic Chemistry is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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        Value: 10.1021/jo8003138
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      – Code: eng
        Text: English
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        PageCount: 10
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      – SubjectFull: Stereochemistry
        Type: general
      – SubjectFull: Chemical structure
        Type: general
      – SubjectFull: Conformational analysis
        Type: general
      – SubjectFull: Chemical reactions
        Type: general
      – SubjectFull: Nuclear isomers
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      – TitleFull: Stereostructure Assignment of Flexible Five-Membered Rings by GIAO 13C NMR Calculations: Prediction of the Stereochemistry of Elatenyne.
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              Text: 6/6/2008
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              Y: 2008
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