Proton magnetic resonance spectra and assignments of strychnine and selectively deuterated strychnine

Carter, James C.; Luther, George W.; Long, T. C.

doi:10.1016/0022-2364(74)90181-4

Cited by 21 publications

(10 citation statements)

References 18 publications

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“…To evaluate the potential of the analytical contributions of ANAD NMR to the structural analysis of natural products, we first investigated strychnine ( 1 ) (Figure a). This heptacyclic structure (six stereogenic carbon atoms and six prochiral CH 2 groups) has been used as a “model” molecule over decades and has been investigated by theoretical approaches, by isotropic NMR, , as well as in oriented media using RDCs, ,, or RCSAs, , as anisotropic data. Residual dipolar couplings ( 1 D CH ) for 1 were recorded in PBLG and poly(γ-ethyl- l -glutamate) (PELG) polypeptide. , …”

Section: Resultsmentioning

confidence: 99%

“…as "model" molecule over decades and has been investigated either by theoretical approaches, 57 isotropic NMR 56,68 as well as in oriented media using RDCs, 30,58,59 or RCSAs, 29,30 as anisotropic data. Residual dipolar couplings ( 1 D CH ) for 1 were recorded in PBLG and PELG polypeptide.…”

Section: Strychninementioning

confidence: 99%

“…As a proof of concept, we have chosen two complex, chiral, polycyclic natural products (Figure ). The first is strychnine ( 1 ), an alkaloid-type poison but a “beloved” model compound for NMR spectroscopists over the decades, − and the second one is artemisinin ( 2 ), an antimalarial drug used against Plasmodium falciparum malaria. ,− Throughout this work, we will apply the MSpin-RQC computational protocol recently described (Figures SI-1 and SI-2). …”

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confidence: 99%

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Deuterium Residual Quadrupolar Couplings: Crossing the Current Frontiers in the Relative Configuration Analysis of Natural Products

et al. 2020

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Determination of the 3D structure (configuration and preferred conformation) of complex natural and synthetic organic molecules is a long-standing but still challenging task for chemists, with various implications in pharmaceutical sciences whether or not these substances have specific bioactivities. NMR in aligning media, either lyotropic liquid crystals (LLC) or polymer gels, in combination with molecular modelling is a unique framework to solve complex structural problems whose analytical wealth lies in the establishment of non-local structural correlations. As an alternative to already well-established anisotropic NMR parameters, such as RDCs (residual dipolar couplings) and RCSAs (residual chemical shift anisotropies), it is shown here that deuterium residual quadrupolar couplings ( 2 H-RQCs) can be extracted from 2 H 2D-NMR spectra recorded at natural abundance level in samples oriented in a homopolypeptide LLC (PBLG). These 2 H-RQCs were successfully used to address non-trivial structural problems in organic molecules. The performance and scope of this new tool is examined for two natural chiral compounds of pharmaceutical interest (strychnine and artemisinin). This is the first report in which the 3D structure/relative configuration of complex bioactive molecules is unambiguously determined using only 2 H-RQCs, being in this case at 2 H natural abundance.

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Section: Resultsmentioning

confidence: 99%

Section: Strychninementioning

confidence: 99%

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confidence: 99%

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Deuterium Residual Quadrupolar Couplings: Crossing the Current Frontiers in the Relative Configuration Analysis of Natural Products

et al. 2020

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“…The coupling constants obtained in this work from non-overlapping multiplets using the Hoye- 5 Golotvin, 7 modified J-doubling 9 and ACCA methods are listed in Table 2 together with values previously obtained by simple analysis of distances between peaks (Peak picking analysis). 19 For brevity, we concentrate here on the analysis of just two signals, those of H-15a and H-22. At first sight, the H-15a signal (Fig.…”

Section: Strychninementioning

confidence: 99%

A two-stage approach to automatic determination of1H NMR coupling constants

Cobas¹,

Constantino-Castillo

Martín-Pastor

et al. 2005

Magn. Reson. Chem.

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(1)H NMR scalar coupling constants are a rich source of information on molecular structure, but their extraction from spectra can be less than straightforward. Previous approaches to J extraction include methods proposed by Hoye, Golotvin, and the 'modified J-doubling' method. Here we describe the ACCA method, currently implemented in the NMR package MestReC, which allows a high degree of automation in the extraction of coupling patterns even in the case of complex multiplets with sublinewidth splitting. The new approach is illustrated by application to strychnine, for which it has detected previously unreported couplings.

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“…As a model system, strychnine, which contains seventeen nonequivalent protons within the region from 4.3 to 1.2 ppm, was chosen. In addition to providing a sufficiently complex model, the examination of Dreiding models also suggested that several long-range coupling pathways which have not been previously reported (6,7) should exist for strychnine. Finally, since response intensity in the proton double quantum experiment is governed by the optimization of the delay, , employed when the double quantum coherence is created, the proton double quantum experiment also provides an independent means of probing the size of the geminal couping between the H17a-H17b pair.…”

mentioning

confidence: 94%

Proton Double Quantum and Relayed Proton Double Quantum Coherence Two-Dimensional NMR Mapping of Proton-Proton Connectivity Networks in Natural Products: a Model Study of Strychnine

Craig¹,

Martin²

1986

J. Nat. Prod.

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Proton magnetic resonance spectra and assignments of strychnine and selectively deuterated strychnine

Cited by 21 publications

References 18 publications

Deuterium Residual Quadrupolar Couplings: Crossing the Current Frontiers in the Relative Configuration Analysis of Natural Products

Deuterium Residual Quadrupolar Couplings: Crossing the Current Frontiers in the Relative Configuration Analysis of Natural Products

A two-stage approach to automatic determination of1H NMR coupling constants

Proton Double Quantum and Relayed Proton Double Quantum Coherence Two-Dimensional NMR Mapping of Proton-Proton Connectivity Networks in Natural Products: a Model Study of Strychnine

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