Magnetic Resonance in Chemistry

Cover image for Magnetic Resonance in Chemistry

January 2010

Volume 48, Issue 1

Pages 1–89

  1. Research Articles

    1. Top of page
    2. Research Articles
    3. Spectral Assignments and Reference Data
    4. Book Reviews
    1. Toward multipurpose NMR experiments (pages 1–8)

      Judith Schlagnitweit, Gerhard Zuckerstätter and Norbert Müller

      Version of Record online: 28 OCT 2009 | DOI: 10.1002/mrc.2527

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      Storing individual phase cycling steps separately instead of immediate co-adding them introduces an additional dimension to conventional pulsed NMR experiments. From such a single ‘super-experiment’ different types of spectral information are derived a posteriori by complex linear combinations. Using this approach one can increase the overall efficiency of a set of experiments substantially.

    2. 13C NMR discrimination of regioisomeric bispyrroloquinone/bispyrroloiminoquinone ring systems (pages 9–12)

      Stefan Chassaing and Evelyne Delfourne

      Version of Record online: 12 OCT 2009 | DOI: 10.1002/mrc.2529

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      The structural assignment of bispyrroloquinone and bispyrroloiminoquinone regioisomers was achieved using 13C NMR spectral data.

    3. Self-association promoted conformational transition of (3R,4S,8R,9R)-9-[(3,5-bis(trifluoromethyl)phenyl))-thiourea](9-deoxy)-epi-cinchonine (pages 13–19)

      Péter Király, Tibor Soós, Szilárd Varga, Benedek Vakulya and Gábor Tárkányi

      Version of Record online: 27 OCT 2009 | DOI: 10.1002/mrc.2531

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      Self-association of the catalyst promotes the interconversion of two monomeric intramolecularly hydrogen-bonded quinoline rotamers.

    4. Simultaneous measurement of N[BOND]H and Cα[BOND]Hα coupling constants in proteins (pages 20–24)

      David Pantoja-Uceda and Jorge Santoro

      Version of Record online: 23 OCT 2009 | DOI: 10.1002/mrc.2532

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      We present a pulse sequence, for the simultaneous measurement of N[BOND]H and Cα[BOND]Hα couplings in double-labeled proteins from 2D spectra. The proposed sequence, a modification of the HN(CO)CA experiment, combines the J-modulation method and the IPAP scheme.

    5. The reaction of spiro[indoline-naphthopyrans] with nitrogen oxides. Not a case of biradical double trapping (pages 25–37)

      Angelo Alberti, Paola Astolfi, Mylène Campredon, Lucedio Greci, Maurizio Guerra, Dante Macciantelli and Elena Plescia

      Version of Record online: 4 NOV 2009 | DOI: 10.1002/mrc.2533

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      The reaction of seven differently substituted spiro[indoline-naphthopyrans] with nitric oxide led to the EPR detection of iminoxy radicals resulting from the opening of the indolinic system. DFT calculations support the identification of the observed radicals. The process is believed to be triggered by adventitious nitrogen dioxide formed by reaction of nitric oxide with traces of oxygen remaining in the system even after thorough nitrogen purging.

    6. New oxidized sterols from Aspergillus awamori and the endo-boat conformation adopted by the cyclohexene oxide system (pages 38–43)

      Hao Gao, Kui Hong, Guo-Dong Chen, Chuan-Xi Wang, Jin-Shan Tang, Yang Yu, Miao-Miao Jiang, Man-Mei Li, Nai-Li Wang and Xin-Sheng Yao

      Version of Record online: 28 OCT 2009 | DOI: 10.1002/mrc.2536

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      Two new oxidized sterols (22E-7α-methoxy-5α,6α-epoxyergosta-8(14),22-dien-3β-ol (1) and 22E-3β-hydroxy-5α,6α,8α,14α-diepoxyergosta-22-en-7-one (2)) were obtained from a mangrove fungus Aspergillus awamori. The NMR data and complete assignments for both DMSO-d6 and CDCl3 were given and their cytotoxic activity against A549 cell line was evaluated. Furthermore, the detailed conformation analysis for ring B (cyclohexene oxide system) of sterol 1 was given based on the NOEs. The endo-boat conformation was considered as the preferred conformation for ring B rather than half-chair conformation.

    7. Structural trends of 77Se[BOND]1H spin–spin coupling constants and conformational behavior of 2-substituted selenophenes (pages 44–52)

      Yury Yu. Rusakov, Leonid B. Krivdin, Stephan P. A. Sauer, Ekaterina P. Levanova and Galina G. Levkovskaya

      Version of Record online: 28 OCT 2009 | DOI: 10.1002/mrc.2537

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      Experimental measurements and SOPPA calculations of 77Se[BOND]1H spin-spin coupling constants together with theoretical energy-based conformational analysis in the series of 2-substituted selenophenes have been carried out. A new basis set optimized for the calculation of 77Se[BOND]1H spin-spin coupling constants has been introduced by extending the aug-cc-pVTZ-J basis for selenium. Most of spin-spin coupling constants under study, especially vicinal 77Se[BOND]1H couplings, demonstrated a remarkable stereochemical behavior in respect with the internal rotation of the substituent in the 2-position of the selenophene ring which is of major importance in the stereochemical studies of the related organoselenium compounds.

    8. Complete experimental and theoretical proton and carbon nuclear magnetic resonance spectral assignments, molecular structure and conformational study of 1-cyclohexylpiperazine and 1-(4-pyridyl)piperazine (pages 53–60)

      Özgür Alver

      Version of Record online: 4 NOV 2009 | DOI: 10.1002/mrc.2538

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      1H, 13C, DEPT, COSY, HETCOR and INADEQUATE NMR spectra and 13C, 15N CP/MAS NMR spectra of 1-chpp and 1-4pypp were reported. 1H and 13C nuclear magnetic shielding tensors were calculated with density functional theory for the most stable two conformers.

    9. 15N and 13C NMR chemical shifts of 6-(fluoro, chloro, bromo, and iodo)purine 2′-deoxynucleosides: measurements and calculations (pages 61–67)

      Shi Bai, Olga Dmitrenko and Cecil Dybowski

      Version of Record online: 20 NOV 2009 | DOI: 10.1002/mrc.2541

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      The effect of halogen substitution on 15N and 13C chemical shifts of substituted purine 2′-deoxynucleoside derivatives has been determined experimentally and by DFT calculations.

    10. Difluorobenzenes revisited: an experimental and theoretical study of spin–spin coupling constants for 1,2-, 1,3-, and 1,4-difluorobenzene (pages 68–73)

      Ibon Alkorta, Fernando Blanco, Janet E. Del Bene, José Elguero, Laura Hernández-Folgado and María-Luisa Jimeno

      Version of Record online: 25 NOV 2009 | DOI: 10.1002/mrc.2543

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      Spin-spin coupling constants (SSCCs) of 1,2-, 1,3-, and 1,4-difluorobenzene have been analyzed by comparison with computed SOPPA and EOM-CCSD coupling constants. Eighty experimental values have been analyzed using SOPPA calculations, and a subset of 40 values using both SOPPA and EOM-CCSD approaches. One-bond coupling constants 1J(C-C) and 1J(C-F) are better described at EOM-CCSD, while one-bond 1J(C-H) values are better described at SOPPA. An empirical equation is presented which allows for the prediction of unknown coupling constants from computed SOPPA values.

  2. Spectral Assignments and Reference Data

    1. Top of page
    2. Research Articles
    3. Spectral Assignments and Reference Data
    4. Book Reviews
    1. 1H and 13C NMR assignments of all three isomeric o-fluoronaphthaldehydes and three o-fluorophenanthrene aldehydes (pages 74–79)

      Carl A. Busacca, Scot Campbell, Nina C. Gonnella and Chris H. Senanayake

      Version of Record online: 6 OCT 2009 | DOI: 10.1002/mrc.2523

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      Complete structural and spectroscopic assignments of key fluorinated chiral catalyst starting materials has been achieved, using 19F–1H HOESY as a key enabling NMR technique.

    2. Structure elucidation and NMR assignments for two xanthone derivatives from a mangrove endophytic fungus (No. ZH19) (pages 80–82)

      Zhongjing Huang, Ruiyun Yang, Xianhong Yin, Zhigang She and Yongcheng Lin

      Version of Record online: 11 NOV 2009 | DOI: 10.1002/mrc.2539

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      The structure elucidations and complete 1H and 13C NMR assignments are reported for two new xanthone derivatives: 1,7-dihydroxy-2-methoxy-3-(3-methylbut-2-enyl)-9H-xanthen-9-one (1) and 1-hydroxy-4,7-dimethoxy-6-(3-oxobutyl) -9H-xanthen-9-one (2). Both of these secondary metabolites were isolated from the fermentation medium of amangrove endophytic fungus (No. ZH19). Preliminary pharmacological test showed that compounds (1) and (2) inhibited KB cells with IC50 values of 20 and 35µmol/ml, and KBV200 cells with IC50 values of 30 and 41µmol/ml, respectively.

    3. Complete 1H and 13C NMR data assignment of new constituents from Severinia buxifolia (pages 83–88)

      Markus Bacher, Günter Brader, Harald Greger and Otmar Hofer

      Version of Record online: 24 NOV 2009 | DOI: 10.1002/mrc.2548

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      Phytochemical analysis of different organs of the rutaceaeous plant Severinia buxifolia led to the isolation of a new limonoid, a new acridone alkaloid, and a new flavone. Structure elucidation and signal assignment were achieved by the extensive use of 1D and 2D NMR experiments (selective 1D NOE, COSY, NOESY, HSQC, HMBC).

  3. Book Reviews

    1. Top of page
    2. Research Articles
    3. Spectral Assignments and Reference Data
    4. Book Reviews