The NMR spectra and conformations of cyclic compounds–III: The conformations of some pinane derivatives

Abraham, Raymond J.; Bottom, F. H.; Cooper, M. Ashley; Salmon, J. R.; Whittaker, D.

doi:10.1002/mrc.1270010108

Cited by 20 publications

(12 citation statements)

References 14 publications

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“…Concerning the cyclobutane part of the system, these are generally in accord with previous studies [5] [6], confirming in particular, that the coupling constant between the protons at C (7,8) is greater when these are cis than when they are trans [7]. The use of coupling constants as well as consideration of the influence of various substituents on the chemical shift of the gem-dimethyl groups [8], has led to the establishment of preferred conformations for simple pinane derivatives .…”

Section: -Facesupporting

confidence: 91%

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The Configuration of Tricyclo [7.1.1.0^2,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

Thomas

Thommen

Becker

1981

Helvetica Chimica Acta

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SummaryA full discussion of the configuration of tricyclo [7.1 .1.02*7]undecanes related to cis-10, lO-dimethyltricyclo [7.1.1 .02,7]undec-2-en-4-one (2), the Robinson annelation product from norpinone 1 and 3-buten-2-one is given, based on 360-MHz-NMR. spectra. Nuclear Overhauser effects confirm the cis configuration of 2, and show that the saturated ketone 10, obtained by catalytic hydrogenation, is also all-cis with the cyclohexanone ring in the boat conformation. The parent hydrocarbon, cis-10, lO-dimethyltricyclo [7.1.1 .02.7]undecane is compared with one of the corresponding trans isomers prepared from pinocarvone (14). The stereochemistry of metal hydride reduction and Grignard reaction of 2 is examined.Earlier work has suggested that 'Tricyclone"), the compound formed by Robinson annulation of 3-buten-2-one to the norpinone 1 should be ascribed the cis configuration 2 [I]. This attribution is supported by the observations of Barthklkmy & BessiBre [2] [3] who showed that under non-solvating conditions, the ions formed by addition of HBr to a-pinenes rearrange by migration of the gem-dimethyl bridge (to bornanes) in the case of cis-substitution, and of the methylene bridge (to fenchanes) in the case of trans-substitution. The hydrocarbon 3 derived from 2 rearranges to the bornane 4 under these conditions. Nevertheless, direct spectral evidence for the configuration of 2 was lacking, and we now present a full discussion of the NMR. spectra of this and related substances, and describe the stereochemistry of various reductions of 2.Base-catalyzed deuterium exchange [4] of 2 yielded mainly the tetradeuteriated compound 5, and it was possible to analyze the 360-MHz-'H-NMR. spectrum in detail (see Table I for a list of the chemical shifts of 2, 5, and other related I )Brand name of Firmenich SA.

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Section: -Facesupporting

confidence: 91%

“…Thus Table 2 shows a lowering of the coupling constant J(6P,7) (i.e. a narrowing of the dihedral angle) and a rise in the coupling constant J (6a, 7).…”

mentioning

confidence: 95%

The Configuration of Tricyclo [7.1.1.0^2,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

Thomas

Thommen

Becker

1981

Helvetica Chimica Acta

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“…An important terpene subgroup is the pinanes with a fused four‐membered ring. We have previously undertaken extensive studies of the 1 H‐NMR spectra of these molecules, confirming their structures and in several cases suggesting their conformations. However, since this early work, there has been no comprehensive attempt to calculate the 1 H chemical shifts of these molecules.…”

Section: Introductionmentioning

confidence: 63%

“…Also, the NMR data should be complete, and the spectrum fully assigned in non‐polar solvents. The analysis of the 1 H‐NMR spectra of 19 derivatives of pinane in non‐polar solvents has given earlier, and we will use this data to parameterize the HSPEC model.…”

Section: Introductionmentioning

confidence: 99%

A molecular mechanics and ab initio prediction of the ¹H chemical shifts of pinanes

Abraham

Cooper

2017

Magnetic Reson in Chemistry

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Molecular mechanics calculations plus the application of a refined Karplus equation gave the conformations of 19 pinanes. These range from a Y-shaped geometry in the apopinene and α-pinene series to a pseudo chair conformation in β-pinene, nopinone and verbanone, a flattened chair in pinocarvone and the pinocarveols and a distorted Y shape for iso-verbanone. These structures were then used as input to predict the H chemical shifts of these compounds by semi-empirical ( H-NMR spectra (HSPEC)) and ab initio gauge-invariant atomic orbital (GIAO) calculations, the latter at the B3LYP hybrid density functional theory level using 6-31++G** basis set. The two methods gave generally good agreement with the 184 observed shifts with root mean square (RMS) errors 0.07 ppm (HSPEC) and 0.10 ppm (GIAO), but the GIAO calculations gave several significant (>0.25 ppm) errors. One was for the H proton in apopinenone and other α,β unsaturated ketones; the others occurred for protons in close proximity to hydroxyl groups. To provide more information, smaller analogues of known geometry and chemical shifts were subject to the same analysis. In cyclopentenone, the Gaussian geometry gave good agreement with the observed shifts, but the MMFF94, MMX and MM3 geometries all gave errors for different protons. These results show clearly that the molecular geometries of the α,β unsaturated ketones are responsible for the errors. The errors for the alcohols were examined using ethanol as model and were shown to be due to the different possible conformations of the OH group. Similar GIAO calculations on substituted methanes gave good agreement for the methyl compounds but poor agreement for di and tri halosubstituted methanes. The aforementioned method of molecular mechanics plus GIAO calculations is shown to be a very useful tool for the investigation of molecular geometries and conformations. However, multihalogen compounds may require different basis sets for accurate calculations. Copyright © 2017 John Wiley & Sons, Ltd.

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“…8 ) The conformation of compounds 3, 4, 9 and 10 was a bridged boat* form, in which the C3 puckers up to the C9 methyl group. In these, the C2-C3-C4 plane deviates from the CI-C2-C4- hand, compounds 5 ~ 8 were described as a bridged chair form which was reported for nopinone 14 ) and 3-amino-2,BH-pinanes. 12 ) As seen in Band C of Fig.…”

Section: Coupling Constantsmentioning

confidence: 80%

Conformational Analysis of Verbenols and Related Alcohols by PMR Spectra with a Chemical Shift Reagent

Nishino¹,

Takayanagi²

1979

Agricultural and Biological Chemistry

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The NMR spectra and conformations of cyclic compounds–III: The conformations of some pinane derivatives

Cited by 20 publications

References 14 publications

The Configuration of Tricyclo [7.1.1.0^2,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

The Configuration of Tricyclo [7.1.1.0^2,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

A molecular mechanics and ab initio prediction of the ¹H chemical shifts of pinanes

Conformational Analysis of Verbenols and Related Alcohols by PMR Spectra with a Chemical Shift Reagent

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The NMR spectra and conformations of cyclic compounds–III: The conformations of some pinane derivatives

Cited by 20 publications

References 14 publications

The Configuration of Tricyclo [7.1.1.02,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

The Configuration of Tricyclo [7.1.1.02,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

A molecular mechanics and ab initio prediction of the 1H chemical shifts of pinanes

Conformational Analysis of Verbenols and Related Alcohols by PMR Spectra with a Chemical Shift Reagent

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The Configuration of Tricyclo [7.1.1.0^2,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

The Configuration of Tricyclo [7.1.1.0^2,7]undecanes and the Stereochemistry of the Reduction of Tricyclone

A molecular mechanics and ab initio prediction of the ¹H chemical shifts of pinanes