Solid-state13C chemical shift tensors in terpenes. Part I. Spectroscopic methods and chemical shift structure correlations in caryophyllene oxide

Harper, James K.; McGeorge, Gary; Grant, David M.

doi:10.1002/(sici)1097-458x(199806)36:13<s135::aid-omr312>3.0.co;2-9

Cited by 33 publications

(41 citation statements)

References 4 publications

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“…In addition, 4 mg of a known compound (4,12,12-trimethyl-9-methylene-5-oxatricyclo[8.2.0.04,6] dodecane or β -caryophyllene oxide) was isolated. This compound was identified by comparison of its 1H- and 13C-NMR and mass values with those cited in literature ( Harper et al, 1998 ).…”

Section: Methodsmentioning

confidence: 99%

Phloroglucinol and Terpenoid Derivatives from Hypericum cistifolium and H. galioides (Hypericaceae)

et al. 2016

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A new simple phloroglucinol derivative characterized as 1-(6-hydroxy-2,4-dimethoxyphenyl)-2-methyl-1-propanone (1) was isolated from Hypericum cistifolium (Hypericaceae) as a major constituent of the non-polar plant extract. Minor amounts of this new compound, in addition to two known structurally related phloroglucinol derivatives (2 and 3), and two new terpenoid derivatives characterized, respectively, as 2-benzoyl-3,3-dimethyl-4R,6S-bis-(3-methylbut-2-enyl)-cyclohexanone (4a) and 2-benzoyl-3,3-dimethyl-4S,6R-bis-(3-methylbut-2-enyl)-cyclohexanone (4b), were isolated from a related species, H. galioides Lam. The chemical structures were established using 2D-NMR spectroscopy and mass spectrometry. These compounds were evaluated in vitro for antimicrobial activity against a panel of pathogenic microorganisms and anti-inflammatory activity through inhibition of COX-1, COX-2, and 5-LOX catalyzed LTB4 formation.

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Section: Methodsmentioning

confidence: 99%

Phloroglucinol and Terpenoid Derivatives from Hypericum cistifolium and H. galioides (Hypericaceae)

et al. 2016

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“…Typical assignment methods, such as comparison to solution shifts or computed shifts, 47 are therefore not germane since each position gives two resonances with nearly identical shift values. In a limited number of cases, the solid-state INADEQUATE, UC2QF-COSY or spin diffusion methods 48 have been used to obtain assignments to the asymmetric unit.…”

Section: Methodsmentioning

confidence: 99%

Structural characterization of an anhydrous polymorph of paclitaxel by solid-state NMR

Heider¹,

Harper²,

Grant³

2007

Phys. Chem. Chem. Phys.

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The three-dimensional structure of a unique polymorph of the anticancer drug paclitaxel (Taxol) is established using solid state NMR (SSNMR) tensor ((13)C & (15)N) and heteronuclear correlation ((1)H-(13)C) data. The polymorph has two molecules per asymmetric unit (Z' = 2) and is thus the first conformational characterization with Z' > 1 established solely by SSNMR. Experimental data are correlated with structure through a series of computational models that extensively sample all conformations. For each computational model, corresponding tensor values are computed to supply comparisons with experimental information which, in turn, establishes paclitaxel's structure. Heteronuclear correlation data at thirteen key positions provide shift assignments to the asymmetric unit for each comparison. The two distinct molecules of the asymmetric unit possess nearly identical baccatin III moieties with matching conformations of the C10 acetyl moiety and, specifically, the torsion angle formed by C30-O-C10-C9. Additionally, both are found to exhibit an extended conformation of the phenylisoserine sidechain at C13 with notable differences in the dihedral angles centered around the rotation axes of O-C13, C2'-C1' and C3'-C2'.

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“…1 and Eq. [14], the six geometric symmetry shift components for the icosahedrons are given by the transformation matrix T from the Cartesian to the icosahedral representations becomes:…”

Section: Metric Matrices For Other Chemical-shift Representationsmentioning

confidence: 99%

“…Both icosahedral tensors ( 1 d icos or 2 d icos ) have identical transformation properties as found in Eqs. [14] and [15], and m ¼ Z. Multiplying expressions and matrices in Eqs. [14] to [18] yields the metric of the icosahedral representation as follows:…”

Section: Metric Matrices For Other Chemical-shift Representationsmentioning

confidence: 99%

Metric spaces in NMR crystallography

Grant

Halling

2009

Concepts Magnetic Resonance

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ABSTRACT:The anisotropic character of the chemical shift can be measured by experiments that provide shift tensor values and comparing these experimental components, obtained from microcrystalline powders, with 3D nuclear shielding tensor components, calculated with quantum chemistry, yields structural models of the analyzed molecules. The use of a metric tensor for evaluating the mean squared deviations, d 2 , between two or more tensors provides a statistical way to verify the molecular structure governing the theoretical shielding components. The sensitivity of the method is comparable with diffraction methods for the heavier organic atoms (i.e., C, O, N, etc.) but considerably better for the positions of H atoms. Thus, the method is especially powerful for H-bond structure, the position of water molecules in biomolecular species, and other proton important structural features, etc. Unfortunately, the traditional Cartesian tensor components appear as reducible metric representations and lack the orthogonality of irreducible icosahedral and irreducible spherical tensors, both of which are also easy to normalize. Metrics give weighting factors that carry important statistical significance in a structure determination. Details of the mathematical analysis are presented and examples given to illustrate the reason nuclear magnetic resonance are rapidly assuming an important synergistic relationship with diffraction methods (X-ray, neutron scattering, and high energy synchrotron irradiation).

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Solid-state13C chemical shift tensors in terpenes. Part I. Spectroscopic methods and chemical shift structure correlations in caryophyllene oxide

Cited by 33 publications

References 4 publications

Phloroglucinol and Terpenoid Derivatives from Hypericum cistifolium and H. galioides (Hypericaceae)

Phloroglucinol and Terpenoid Derivatives from Hypericum cistifolium and H. galioides (Hypericaceae)

Structural characterization of an anhydrous polymorph of paclitaxel by solid-state NMR

Metric spaces in NMR crystallography

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