1H and 13C NMR spectral study of some 3‐aryl‐5r‐aryl‐6t‐carbethoxycyclohex‐2‐enones—a study of four‐bond 1H1H couplings

Yuvaraj, C.; Pandiarajan, K.

doi:10.1002/mrc.2724

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…However, because of the allylic orientational effect, a slight barrier may exist, thus favoring only one of the conformations with aquatolide then being rendered semirigid. A study involving a structural arrangement similar to the present case (6- vs 8-membered ring in aquatolide) was observed for 3-aryl-5r-aryl-6t-carbethoxycyclohex-2-enones . The largest coupling constant is attributed to a geminal J H‑5a,H‑5b coupling (−20.006 Hz), which separates the signal into two almost baseline separated subpatterns.…”

Section: Resultssupporting

confidence: 73%

“…A study involving a structural arrangement similar to the present case (6- vs 8-membered ring in aquatolide) was observed for 3-aryl-5r-aryl-6t-carbethoxycyclohex-2-enones. 23 The largest coupling constant is attributed to a geminal J H-5a,H-5b coupling (−20.006 Hz), which separates the signal into two almost baseline separated subpatterns. The 3 J H-5a,H-4a and 3 J H-5a,H-4b couplings have already been described.…”

Section: Resultsmentioning

confidence: 96%

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Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Pauli

Niemitz²,

Bisson

et al. 2016

J. Org. Chem.

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The revision of the structure of the sesquiterpene aquatolide from a bicyclo[2.2.0]hexane to a bicyclo[2.1.1]hexane structure using compelling NMR data, X-ray crystallography, and the recent confirmation via full synthesis exemplify that the achievement of “structural correctness” depends on the completeness of the experimental evidence. Archived FIDs and newly acquired aquatolide spectra demonstrate that archiving and rigorous interpretation of 1D 1H NMR data may enhance the reproducibility of (bio)chemical research and curb the growing trend of structural misassignments. Despite being the most accessible NMR experiment, 1D 1H spectra encode a wealth of information about bonds and molecular geometry that may be fully mined by 1H iterative full spin analysis (HiFSA). Fully characterized 1D 1H spectra are unideterminant for a given structure. The corresponding FIDs may be readily submitted with publications and collected in databases. Proton NMR spectra are indispensable for structural characterization even in conjunction with 2D data. Quantum interaction and linkage tables (QuILTs) are introduced for a more intuitive visualization of 1D J-coupling relationships, NOESY correlations, and heteronuclear experiments. Overall, this study represents a significant contribution to best practices in NMR-based structural analysis and dereplication.

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Section: Resultssupporting

confidence: 73%

Section: Resultsmentioning

confidence: 96%

Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Pauli

Niemitz²,

Bisson

et al. 2016

J. Org. Chem.

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“…This result attests to a hindered rotation of the thiophene substituent due to the steric effect of the carbonyl group. This is associated with the ring size of the bridge, because this phenomenon is not observed in the cyclopentenone series studied previously. , According to the literature data, analysis of NMR spectra (section I.6 in the SI), and the calculated structure optimization (vide infra), the cyclohexenone moiety in compounds 4 in a wide range of temperatures from 343 to 303 K exists in the sofa (half-chair) conformation; i.e., the dynamic NMR effect is not a result of the conformational transformation of the cyclohexenone ring.…”

Section: Resultsmentioning

confidence: 85%

Structural and Spectral Properties of Photochromic Diarylethenes: Size Effect of the Ethene Bridge

et al. 2017

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The effect of the size of the ethene bridge on the structural and spectral properties of photochromic diarylethenes, which remains a poorly understood phenomenon, was studied as applied to diarylethenes containing unsymmetrical (cyclohexenone and cyclopentenone) and symmetrical (cyclohexene and cyclopentene) ethene bridges. Thiophene, oxazole, and imidazole derivatives were used as aryl moieties. An increase in the size of the ethene bridge in the cycloalkenone series was found to be accompanied by a hypsochromic shift of the absorption maximum of the photoinduced form, whereas no difference was found for cycloalkenes. A detailed analysis of the NMR spectra (including 2D experiments) revealed previously unknown effects associated with the existence of an intramolecular hydrogen bond (CH···N) between the six-membered ethene bridge and the azole substituents. The NMR experimental data obtained were confirmed by DFT quantum chemical calculations and X-ray analysis. It was found that an intramolecular hydrogen bond favors an increase of the quantum yield of the photocyclization reaction.

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Synthesis and 1H and 13C NMR spectral study of some r(2),c(4)-bis(isopropylcarbonyl)-c(5)-hydroxy-t(5)-methyl-t(3)-substituted phenyl, cyclohexanones and their oximes

Balachander

Sameera

Mohan

2016

Journal of Molecular Structure

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¹H and ¹³C NMR spectral study of some 3‐aryl‐5r‐aryl‐6t‐carbethoxycyclohex‐2‐enones—a study of four‐bond ¹H¹H couplings

Cited by 4 publications

References 12 publications

Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Structural and Spectral Properties of Photochromic Diarylethenes: Size Effect of the Ethene Bridge

Synthesis and 1H and 13C NMR spectral study of some r(2),c(4)-bis(isopropylcarbonyl)-c(5)-hydroxy-t(5)-methyl-t(3)-substituted phenyl, cyclohexanones and their oximes

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