What question did this study set out to answer?

To examine steric and conformational influences on carbon-13 chemical shieldings using methyl-substituted cyclohexanones and cyclopentanones as model systems.

January 15, 1974Canadian Journal of Chemistry

13C Nuclear Magnetic Resonance Studies. 34. The 13C Spectra of Several Methylcyclopentanones and -cyclohexanones

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Authors

JSJ. B. StothersWestern University CTC. T. TanNational University of Singapore

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Implication

Spectroscopic analysis demonstrates conformation-dependent carbon-13 shielding trends in methyl-substituted cyclic ketones, highlighting steric effects in stereochemical assignment.

Key Points

To examine steric and conformational influences on carbon-13 chemical shieldings using methyl-substituted cyclohexanones and cyclopentanones as model systems.
Determined carbon-13 nuclear magnetic resonance spectra for 16 methyl-substituted cyclohexanones and 15 methylcyclopentanones.
Assigned individual resonance signals through systematic intercomparison of shielding values across both compound series.
Cyclohexanones preferentially adopt chair conformations with ring distortion observed in tetramethyl derivatives, whereas cyclopentanones strongly favor half-chair conformations puckered at C-3 and C-4.
Pronounced carbon-13 shielding differences emerge between cis and trans isomers, facilitating stereochemical assignment of cis-trans dimethyl derivatives.
Sterically crowded delta nuclei in syn-axial arrangements exhibit distinct and marked deshielding effects.

Cite This Study

Stothers et al. (1974) studied this question.

synapsesocial.com/papers/6a973016fe71bc4814a1a564 https://doi.org/10.1139/v74-050

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Implication

Spectroscopic analysis demonstrates conformation-dependent carbon-13 shielding trends in methyl-substituted cyclic ketones, highlighting steric effects in stereochemical assignment.

13C Nuclear Magnetic Resonance Studies. 34. The 13C Spectra of Several Methylcyclopentanones and -cyclohexanones

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Key Points

Cite This Study

13C Nuclear Magnetic Resonance Studies. 34. The 13C Spectra of Several Methylcyclopentanones and -cyclohexanones

Discussion

Member takes

Implication

Key Points

Cite This Study

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