- Carbon-13 NMR Spectra of Some Methyl-Substituted Adamantanones
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The synthesis of 1-methyl- (2), 1,5-dimethyl- (3), and 5,7-dimethyladamantanone (4) and their 13C NMR spectra have been investigated.For the preparation of 3 and 4, some discrepancies existing in the literature are revealed.The carbon-13 NMR resonances of 2, 3, and 4, have been completely assigned from conventional high-resolution spectra with the use of a 1H-13C polarization transfer technique and lanthanide shift reagent experiments.Comparison of the chemical shift values with those of the parent adamantanone (1) and the tetramethyl derivative 5 indicates that the effects of methyl groups on the chemical shifts of adamantanone are similar in direction and magnitude to the effects observed in adamantane.The carbonyl group induces upfield shifts of the signals for carbons across the polycyclic system and for the methyl groups, especially at the adjacent bridgeheads.
- Farcasiu, Dan,Marino, Gaye,Rose, Kenneth D.
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- THE OCTANT RULE. XX. SYNTHESIS AND CIRCULAR DICHROISM OF (1S,5S)-DIMETHYLADAMANTAN-2-ONE -- PREDICTED TO HAVE ZERO COTTON EFFECT
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The title compound was synthesized in optically active form from adamantane.Although the methyl perturbers lie in the extended local symmetry planes of the carbonyl chromophore, and octant and quadrant rules therefore predict they should make no contributions to the Cotton effect (CE), weak negative CEs are found in cyclopentane (Δεmax293 = -0.03) and in CF3CH2OH (Δεmax288 = -0.02) solvents.
- Lightner, David A.,Toan, Vien Van
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p. 4905 - 4916
(2007/10/02)
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