Magnetic Resonance in Chemistry

Cover image for Vol. 50 Issue 1

January 2012

Volume 50, Issue 1

Pages 1–83

  1. Rapid Communications

    1. Top of page
    2. Rapid Communications
    3. Research Articles
    4. MRC Letters
    1. Nuclear magnetic resonance spectroscopic analysis of ethyl ester yield in the transesterification of vegetable oil: an accurate method for a truly quantitative analysis (pages 1–4)

      Giovanni Pimenta Mambrini, Caue Ribeiro and Luiz Alberto Colnago

      Version of Record online: 5 FEB 2012 | DOI: 10.1002/mrc.2831

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      In this communication, the experimental conditions for a truly quantitative nuclear magnetic resonance analysis of biodiesel formation are presented. The longitudinal relaxation time (T1) was measured using an inversion-recovery method, and a maximum value of 2.35 s was obtained for a biodiesel sample. A linear determination coefficient of r2 = 0.99 was obtained when a time delay between pulses longer than 5T1 = 15 s was used, whereas strong deviations were observed when shorter delays were used.

    2. Aligned deuterochloroform in cross-linked polystyrene as a new sample for adjusting the magic angle in HR-MAS (pages 5–6)

      Markus Leutzsch, Matthias Findeisen and Stefan Berger

      Version of Record online: 23 JAN 2012 | DOI: 10.1002/mrc.3789

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      A new and easily usable sample for adjusting the magic angle in a high resolution magic angle spinning (HR-MAS) probe head is a swollen polymer stick in CDCl3.

  2. Research Articles

    1. Top of page
    2. Rapid Communications
    3. Research Articles
    4. MRC Letters
    1. Application of multivariate image analysis in modeling 13C-NMR chemical shifts of mono substituted pyridines (pages 7–15)

      Zahra Garkani-Nejad and Mohammad Ahmadvand

      Version of Record online: 19 JAN 2012 | DOI: 10.1002/mrc.2835

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      Multivariate image analysis (MIA) descriptors have been applied to quantitative structure-property relationship (QSPR) study of 13C-NMR chemical shifts of 2- mono substituted Pyridines. Correlation ranking-principal component regression (CR-PCR) and correlation ranking-principal component-artificial neural networks (CR-PC-ANNs) applied to constructing predictor models.

    2. Comparison of GIAO and CSGT for calculating 13C and 15N nuclear magnetic resonance chemical shifts of substituent neutral 5-aminotetrazole and 5-nitrotetrazole compounds (pages 16–21)

      Yubo Li, Haixiang Gao, Jiaheng Zhang, Songqing Li and Wenfeng Zhou

      Version of Record online: 23 JAN 2012 | DOI: 10.1002/mrc.2840

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      GIAO and CSGT methods are used for calculating chemical shifts of 13C and 15N of tetrazoles. The best approach is GIAO/B3LYP/ aug-cc-pVDZ with IEF-PCM. The calculated 15N chemical shifts can be used to study the intrinsic relationship between structure and explosive properties.

    3. Elucidating ‘undecipherable’ chemical structures using computer-assisted structure elucidation approaches (pages 22–27)

      Mikhail Elyashberg, Kirill Blinov, Sergey Molodtsov and Antony Williams

      Version of Record online: 19 JAN 2012 | DOI: 10.1002/mrc.2849

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      The computer-assisted structure elucidation (CASE) approach was successfully applied to the elucidation of organic structures that seemed unsolvable by classical approaches based on traditional analysis of 2D NMR data. The results obtained lead us to conclude that CASE software should be an integral part of the toolkit for modern structure elucidation approaches. Advanced NMR spectroscopy techniques should be integrated with CASE software approaches for the solution of the most challenging problems.

    4. High-resolution and high-sensitivity 2D homonuclear J-resolved NMR spectroscopy (pages 28–32)

      Agathe Martinez, Flavien Bourdreux, Emmanuel Riguet and Jean-Marc Nuzillard

      Version of Record online: 23 JAN 2012 | DOI: 10.1002/mrc.2850

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      A new implementation of the ALPESTRE processing of 2D homonuclear J-resolved NMR data opens the way to resolution enhancement and strong coupling artifact detection.

    5. Structural and conformational analysis of 1-oxaspiro[2.5]octane and 1-oxa-2-azaspiro[2.5]octane derivatives by 1H, 13C, and 15N NMR (pages 33–39)

      Rubén Montalvo-González and Armando Ariza-Castolo

      Version of Record online: 10 FEB 2012 | DOI: 10.1002/mrc.3792

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      The relative configuration and preferent conformation of 1-oxo and 1-oxo-2-aza- spiro[2.5]octanes were determined by NMR. The data allowed to establish the stereoselectivity of oxidation to the exocyclic double bond C=C and C=N.

    6. NQR parameters of complexes and polarizability effect (pages 40–51)

      Alexey N. Egorochkin, Olga V. Kuznetsova, Nadiya M. Khamaletdinova and Lada G. Domratcheva-Lvova

      Version of Record online: 6 FEB 2012 | DOI: 10.1002/mrc.3795

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      The NQR frequencies (ν), quadrupole coupling constants (e2Qq ⋅ h− 1), and asymmetry parameters (η) depend not only on the inductive and resonance effects but also on the polarizability and steric effects of substituents.

  3. MRC Letters

    1. Top of page
    2. Rapid Communications
    3. Research Articles
    4. MRC Letters
    1. 1H and 13C NMR characterization of new cycloartane triterpenes from Mangifera indica (pages 52–57)

      Carolina Escobedo-Martínez, M. Concepción Lozada, Simón Hernández-Ortega, María Luisa Villarreal, Dino Gnecco, Raúl G. Enríquez and William Reynolds

      Version of Record online: 23 JAN 2012 | DOI: 10.1002/mrc.2836

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      Seven cycloartane-type secondary metabolites were isolated from the stem bark of Mangifera indica. Unambiguous 13C and 1H NMR assignments for three new cycloartanes and four known ones were made.

    2. Characterization of 4,5-Dihydro-1H-Pyrazole Derivatives by 13C NMR Spectroscopy (pages 58–61)

      M. Dora Carrión, Mariem Chayah, Duane Choquesillo-Lazarte, Miguel A. Gallo, Antonio Espinosa, Antonio Entrena and M. Encarnación Camacho

      Version of Record online: 18 JAN 2012 | DOI: 10.1002/mrc.2843

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      The 13C NMR chemical shifts of 19 1-acyl-3-(2-nitrophenyl-5-substituted)-4,5-dihydro-1H-pyrazoles,and 19 1-acyl-3-(2-amino-5-substituted)-4,5-dihydro-1H-pyrazoles, were assigned and discussed using mono- and bi-dimensional resonance techniques.

    3. Synthesis of methoxybenzoflavones and assignments of their NMR data (pages 62–67)

      Doseok Hwang, Geunhyeong Jo, Jiye Hyun, Sung Dae Lee, Dongsoo Koh and Yoongho Lim

      Version of Record online: 8 FEB 2012 | DOI: 10.1002/mrc.3790

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      A phytotoxic root exudate from Acroptilon repens was identified as 7,8-benzoflavone, an inhibitor of cytochrome P450 1A2 and activator of cytochrome P450 3A4. The synthetic 5,6-benzoflavone also is a potent phytotoxin. Six 7,8-benzoflavones and eight 5,6-benzoflavones were synthesized in this study. The NMR data for a few of these compounds have been previously reported; however, the NMR data for most of them have not been reported. For reference purposes, the complete NMR data for the 14 benzoflavones are described.

    4. Unusual open chain quinolinyl peroxol and its alcohol counterpart obtained through a modified Skraup–Doebner–Von Miller quinoline synthesis: theoretical studies and complete 1H- and 13C-NMR assignments (pages 68–73)

      Jean Fotie, Hilaire V. Kemami Wangun, Katelyn Dreux, Thomas Sommerfeld and Jacob Pittman

      Version of Record online: 5 FEB 2012 | DOI: 10.1002/mrc.3791

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      Detailed NMR studies and full 1H and 13C NMR assignments for an unusual open chain quinolinyl peroxol and its alcohol counterpart. The effects of potential hydrogen bondings in 1, 2, and possible 1-1 dimer, 2-2 dimer and in prototypical model systems, as well as the stability of these compounds, were investigated computationally.

    5. Structure elucidation and NMR assignments of new spirosolane alkaloids from Solanum campaniforme (pages 74–78)

      Maria Conceição M. Torres, José Gustavo L. Almeida, Raimundo Braz-Filho, Edilberto R. Silveira and Otília Deusdênia L. Pessoa

      Version of Record online: 10 FEB 2012 | DOI: 10.1002/mrc.3793

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      From the leaves of Solanum campaniforme, two new spirosolane alkaloids β-acetoxyl-(25S)-22βN-spirosol-4-en-3-one (1) and β-hydroxyl-(25S)-22βN-spirosol-4-en-3-one (4) were isolated along with two other known alkaloids of the same class (25S)-22βN-spirosol-1,4-dien-3-one (2) and (25S)-22βN-spirosol-4-en-3-one (3). Their structures were established after detailed 1D and 2D NMR data analyses as well as HRESIMS.

    6. Structure elucidation and complete NMR spectral assignments of glucosylated saponins of cantalasaponin I (pages 79–83)

      Li-ping Kang, Yong-ze Wang, Bing Feng, Hong-zhi Huang, Wen-bin Zhou, Yang Zhao, Cheng-qi Xiong, Da-wei Tan, Xin-bo Song and Bai-ping Ma

      Version of Record online: 10 FEB 2012 | DOI: 10.1002/mrc.3797

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      Five new glucosylated steroidal saponins, cantalasaponin I-B1-I-B5 (1–5), were isolated and purified from the transformed product of the cantalasaponin I by using Toruzyme 3.0 L as biocatalyst. Their structures were elucidated on the basis of MS, 1D and 2D NMR spectral analyses and chemical evidence.

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