Magnetic Resonance in Chemistry

Cover image for Magnetic Resonance in Chemistry

August 2010

Volume 48, Issue 8

Pages 571–659

  1. Research Articles

    1. Top of page
    2. Research Articles
    3. Notes
    4. MRC Letters
    1. Enhanced automated structure elucidation by inclusion of two-bond specific data (pages 571–574)

      Steve F. Cheatham, Mike Kline, Ryan R. Sasaki, Kirill A. Blinov, Mikhail E. Elyashberg and Sergey G. Molodtsov

      Version of Record online: 1 JUN 2010 | DOI: 10.1002/mrc.2622

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      A common problem in computer-assisted structure elucidation is the ambiguity in determining whether a cross peak in HMBC data is the result of 2, 3 or 4-bond correlations. The addition of the 2-bond specific experiment 1,1-ADEQUATE when used in combination with HSQC and HMBC data results in both increased accuracy and in a dramatic decrease in the time necessary for structure calculation. Optimization of sample conditions for use with a cryogenic probe permits routine acquisition of 1,1-ADEQUATE on a few milligrams of sample.

    2. Topotecan dynamics, tautomerism and reactivity—1H/13C NMR and ESI MS study (pages 575–584)

      Karolina Hyz, Robert Kawȩcki, Elżbieta Bednarek, Wojciech Bocian, Jerzy Sitkowski and Lech Kozerski

      Version of Record online: 8 JUN 2010 | DOI: 10.1002/mrc.2625

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      Topotecan NMR parameters were established in water, elimination of N(Me2) in methanol solution (above), quaternization of N(Me2) and alkylation of OH groups are described and structures characterized by HSQC, HMBC, 1H, 13C and ESI MS.

    3. Structural investigation on phenyl- and pyridin-2-ylamino(methylene)naphthalen-2(3H)-one. Substituent effects on the NMR chemical shifts (pages 585–592)

      Taracad K. Venkatachalam, Gregory K. Pierens, Marc R. Campitelli and David C. Reutens

      Version of Record online: 15 JUN 2010 | DOI: 10.1002/mrc.2626

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      Schiff bases bearing phenyl and pyridyl groups were synthesized and the effects of substituent on the NMR chemical shifts discussed.

    4. Temperature- and pressure-dependent study of 35Cl NQR frequency and spin lattice relaxation time in 2,3-dichloroanisole (pages 593–599)

      L. Ramu, K. P. Ramesh, D. Ramananda and R. Chandramani

      Version of Record online: 28 JUN 2010 | DOI: 10.1002/mrc.2627

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      Application of high pressure on solids has both static and dynamic effects. NQR frequency is a good indicator of both these effects exhibiting a non-linear pressure dependence. NQR relaxation effects have been observed due to torsional motion of the molecule along with the the reorientation of the adjacent symmetric mobile group like CH3

    5. Study of liquid–liquid interfaces by an easily implemented localized NMR sequence (pages 600–606)

      Claire Mantel, Pierre-Alain Bayle, Sabine Hediger, Claude Berthon and Michel Bardet

      Version of Record online: 29 JUN 2010 | DOI: 10.1002/mrc.2628

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      A localized 1H NMR sequence to study concentration profiles in the different phases and at the interface of a biphasic system

    6. GIAO DFT 13C/15N chemical shifts in regioisomeric structure determination of fused pyrazoles (pages 607–613)

      Stefano Chimichi, Marco Boccalini, Alessandra Matteucci, Sergey V. Kharlamov, Shamil K. Latypov and Oleg G. Sinyashin

      Version of Record online: 29 JUN 2010 | DOI: 10.1002/mrc.2633

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      The combined use of two-dimensional NMR correlation experiments and GIAO DFT 13C NMR chemical shift (CS) calculations allowed reliable and simple structural determination of regioisomeric pyrazole derivatives. Moreover, results of differential analysis between the calculated 15N NMR CSs for hypothetical structures and the experimental data was more advantageous with respect to 13C because there was no need for correlational analysis: regioisomeric structures could be determined just by direct comparison.

    7. Differentiation between [1,2,4]triazolo[1,5-a] pyrimidine and [1,2,4]triazolo[4,3-a]- pyrimidine regioisomers by 1H[BOND]15N HMBC experiments (pages 614–622)

      Antonio Salgado, Carmen Varela, Ana María García Collazo and Paolo Pevarello

      Version of Record online: 29 JUN 2010 | DOI: 10.1002/mrc.2634

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      Regioisomeric [1,2,4]triazolo[1,5-a] pyrimidine (1) and [1,2,4]triazolo[4,3-a]pyrimidine derivatives (2), respec- tively obtained by condensation of malonoaldehydes with 3-amino- [1,2,4]-triazole or 3,5-diamino-[1,2,4]- triazole precursors, were unambiguously characterized by 1H[BOND]15N HMBC experiments.

    8. NMR investigation of guest–host complex between chloroform and cryptophane C (pages 623–629)

      Z. Takacs, M. Šoltésová, D. Kotsyubynskyy, J. Kowalewski, J. Lang, T. Brotin and J. P. Dutasta

      Version of Record online: 29 JUN 2010 | DOI: 10.1002/mrc.2637

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      Guest–host complex between cryptophane C, possessing two non-equivalent caps, and chloroform is investigated by NMR spectroscopy. The kinetics of the chloroform exchange between the bound and free sites is determined by 1H exchange spectroscopy and the preferential orientation of chloroform molecule with respect to the cryptophane C frame is examined by the NOESY and ROESY experiments. The experimental findings are compared to the results of quantum chemical calculations.

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      Problems, artifacts and solutions in the INADEQUATE NMR experiment (pages 630–641)

      Alex D. Bain, Donald W. Hughes, Christopher K. Anand, Zhenghua Nie and Valerie J. Robertson

      Version of Record online: 29 JUN 2010 | DOI: 10.1002/mrc.2639

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      The INADEQUATE pulse sequence is analyzed step by step to help optimizing the experiment. Results on two natural products are used as illustration. In particular, manipulation of the refocusing time can bring up important long-range correlations.

  2. Notes

    1. Top of page
    2. Research Articles
    3. Notes
    4. MRC Letters
    1. A simple methodology for the determination of fatty acid composition in edible oils through 1H NMR spectroscopy (pages 642–650)

      Andersson Barison, Caroline Werner Pereira da Silva, Francinete Ramos Campos, Fabio Simonelli, Cesar Antonio Lenz and Antonio Gilberto Ferreira

      Version of Record online: 29 JUN 2010 | DOI: 10.1002/mrc.2629

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      Based on the fact that all fatty acid chains are esterified to glycerol, a simple methodology for the determination of the fatty acid composition through 1H NMR is proposed, without the use of mathematical equations. The methodology was successfully applied in the analysis of several edible oils, with equivalent results to those given by the AOAC Official method.

  3. MRC Letters

    1. Top of page
    2. Research Articles
    3. Notes
    4. MRC Letters
    1. NMR studies on chiral intermediates in the total synthesis of (+)-biotin from D-mannose (pages 651–655)

      Wen-xue Chen, Ping Zhang and Fen-er Chen

      Version of Record online: 1 JUN 2010 | DOI: 10.1002/mrc.2619

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      The complete 1H and 13CNMR spectra assignments of six chiral intermediates in the total synthesis of (+)-biotin starting from D-mannose were carried out by using 1D and 2D NMR experiments, including DEPT, COSY, HSQC and HMBC. The absolute stereochemistry and chiral conformations of these compounds were identified by 1D selective NOE spectra.

    2. Structure determination of selaginellins G and H from Selaginella pulvinata by NMR spectroscopy (pages 656–659)

      Yuan Cao, Ji-Jun Chen, Ning-Hua Tan, Yong-Ping Wu, Jie Yang and Qiang Wang

      Version of Record online: 27 MAY 2010 | DOI: 10.1002/mrc.2623

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      Selaginellins G (1) and H (2), two new selaginellin derivatives, were isolated from the whole plant of S. pulvinata. Their structures were elucidated, and complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, 1H[BOND]1HCOSY and ROESY). Compound 1 displayed good antifungal activity against Candida albicans with IC505.3 μg/ml.

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