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  • 1
    Electronic Resource
    Electronic Resource
    Assignment of quaternary carbons via two-bond heteronuclear selective NOE difference, a useful structure elucidation aid (1985)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 185-191 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Very low power irradiation of suitable narrow peaks in the proton frequency range generated NOE enhancement in neighbouring quaternary carbons, positioned two bonds from the irradiated protons. Subsequent FID acquisition under normal broad band decoupling yielded the NOE-containing FID, which, after subtraction of the unperturbed broad band decoupled FID (devoid of NOE), gave the final NOE difference FID to which only the carbons undergoing NOE enhancement had contributed. Fourier transformation of the latter gave the NOE difference spectrum, usually a one- or two-peak spectrum. This technique proved particularly useful for polysubstituted aromatic rings.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260230311
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrogen-bonded 2-hydroxybenzalazines: Complete assignment of 1H and 13C NMR spectra (1985)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 879-881 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 80 MHz 1H NMR and 20 MHz 13C NMR spectra of eleven substited benzalazines (subsituenst: α-methyl, α,α′-dimethyl, 2-hydroxy, 2,2′-dihydroxy, 4-n-octyloxy, 4,4′-di-n-octyloxy) possessing mesogenic acivity have been assigned using a variety of one-dimensional techniques. These include homonuclear NOE measurements, selective heteronuclear 13C{1H} NOE difference spectroscopy, singlefrequency off-resonance decoupling, spin - echo multiplicity sorting (SEFT) and long-range heteronuclear coupling constant determintion via both gated decoupling and selective excitation (DANTE).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260231019
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  • 3
    Electronic Resource
    Electronic Resource
    Indirect 1H—19F—1H and 1H—19F—13C nuclear overhauser enhancements: Anomalous intensity effects and applications in conformational analysis (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 539-543 
    Details
    ISSN: 0749-1581
    Keywords: Indirect heteronuclear NOEs ; 1H-19F-1H and 1H-19F-13C systems ; Three-spin effects ; Anomalous intensity effects ; Conformational analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Indirect nuclear Overhauser enhancements through 19F have been determined for the three-spin systems 1H-19F-1H and 1H-19F-13C by steady-state presaturation of the appropriate proton, and applied to the conformational analysis of 5-bromo-2-fluoro-4-nitroacetanilide. The 1H NOE difference spectra at 400 MHz showed antiphase doublets for protons undergoing simultaneous dipolar relaxation with, and scalar coupling to, 19F. Similarly, in the 13C selective NOE difference spectrum at 100 MHz, the two lines of the fluorine-bearing carbon showed negative enhancement factors of different magnitude on presaturation of the appropriate proton. The use of these anomalous intensity effects in conformational analysis is illustrated.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260250617
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  • 4
    Electronic Resource
    Electronic Resource
    3,6,9-trioxanthracenes and 3,6-dioxa-9-thianthracenes: Conformational analysis and complete assignment of 13C NMR spectra (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 985-986 
    Details
    ISSN: 0749-1581
    Keywords: 13C NMR ; Heteronuclear ; NOE ; Conformation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 20.15 MHz 13C NMR spectra of five 3,6,9-trioxanthracenes and four 3,6-dioxa-9-thianthracenes have been assigned using a variety of one-dimensional techniques. These include spin-echo multiplicity sorting (SEFT), long-range heteronuclear coupling constant determination via gated decoupling and selective heteronuclear 13C{1H} NOE difference spectroscopy. The axial position of substituents on C-10 has been demonstrated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260251112
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  • 5
    Electronic Resource
    Electronic Resource
    Selective heteronuclear NOE enhancements in benzoheterocycles. Effect of ring size on indirect three-spin effects (1988)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 26 (1988), S. 511-517 
    Details
    ISSN: 0749-1581
    Keywords: Heteronuclear NOE ; Selective heteronuclear 13C{1H} NOE ; Indirect Negative NOE ; 13C—1H—{1H} three-spin effects ; Coumarins ; 2(1H)-Quinolones ; Benzo[b]furans ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 80 MHz 1H NMR and 20 MHz 13C NMR spectra of five 4-methylcoumarins, six 4-methyl-2(1H)-quinolones and nine 3-methylbenzo[b]furans, including six new compounds, were fully assigned. Homonuclear 1H{1H} NOEs and selective heteronuclear 13C{1H} NOEs were measured after low-power pre-saturation of the methyl protons. Indirect, negative heteronuclear NOE enhancements were found in suitable three-spin systems of the 13C—1H—{1H} type, and their magnitude was found to be dependent on ring size. The first examples of indirect, heteronuclear NOE enhancements on non-protonated carbons are described.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260260615
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  • 6
    Electronic Resource
    Electronic Resource
    Measurement of long-range heteronuclear selective 13{1H} NOE enhancements: 4- (α-arylethylidene)-2-phenyl-5(4H)-oxazolones (1985)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 23 (1985), S. 1072-1075 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The technique previously described as two-bond heteronuclear selective NOE difference was improved to yield quantitative data on NOE enhancement factors by recording separately the unperturbed and the perturbed FIDs. In this way the E and Z stereoisomers of 4(α-arylethylidene)-2-phenyl-5(4H)-oxazolones were easily distinguished. The latter showed positive NOE ehancements on quaternary carbons placed two, three and four bonds away from the irradiated methyl protons, as well as a negative NOE on a nearby protonated carbon.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260231209
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of long-range 1H—13C coupling constants of cis-verbenol by modified 2D J spectroscopy (1992)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 30 (1992), S. 823-827 
    Details
    ISSN: 0749-1581
    Keywords: Long-range proton-carbon couplings ; Selective 2D J spectroscopy ; cis-Verbenol ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Known selective 2D J-resolved methods for the determination of long-range proton-carbon coupling constants, nJ(C, H), have been modified and improved by introducing an INEPT or refocused INEPT sequence as a preparation period in the Bax-Freeman selective spin-flip method, or using exclusively selective pulses from the decoupler channel in the selective INEPT-2D experiment. The greater sensitivity achieved allowed the determination of these couplings, even for quaternary carbons, in a short acquisition time and with excellent reproducibility for cis-verbenol.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260300904
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  • 8
    Electronic Resource
    Electronic Resource
    Long-range proton-carbon coupling constants. Part IIFor Part I, see Ref. 2. - norbornene systems (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 196-200 
    Details
    ISSN: 0749-1581
    Keywords: selective 2D J-resolved methods ; long-range proton-carbon coupling constants ; norbornene derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Long-range proton-carbon coupling constants, nJCH, were measured for some simple norbornene derivatives. Among the influence of substitution pattern, a study of the experimental influence of the double bond in the norbornene skeleton on 2JCH and 3JCH was made, taking into account the previously published experimental data for analogous saturated systems. These experimental data show that structural groups which are several bonds away from the coupling sites, but close in space, can provide important alternative mechanisms for transmission of the heteronuclear coupling.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330308
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  • 9
    Electronic Resource
    Electronic Resource
    Regioselectivity studies by selective detection of long-range heteronuclear couplings from the SDEPT-1D method (1994)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 32 (1994), S. 343-347 
    Details
    ISSN: 0749-1581
    Keywords: Selective DEPT ; Long-range 1H—13C couplings ; Delective allylation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some regiosomers formed by palladium(0)-catalysed allylation of several ambident heterocyclic nucleophiles, among others, were easily distinguished in very short spectrometer times by selective polarization transfer via DEPT from well resolved protons to long-range coupled carbons using the SDEPT-1D experiment. This pulse sequence was also analysed in terms of the product operator formalism. These structural elucidations can provide useful information about the regioselectivity in these reactions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260320606
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of hydroxyl and carbonyl groups on long-range proton - carbon coupling constants (1994)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 32 (1994), S. 657-664 
    Details
    ISSN: 0749-1581
    Keywords: Long-range proton-carbon coupling constants ; Selective 2D-J spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Long-range 1H—13C coupling constants were measured for some simple, rigid model compounds containing hydroxyl, bromine or carbonyl groups. These were performed using the recently proposed selective J-resolved SPININEP and SDEPT-2D experiments. The geminal and vicinal heteronuclear coupling constant values were analysed in terms of the nature of substituent, the position along the coupling path and the orientation of the substituent relative to the bounds. In some cases, through-space interactions of the substituent group were also observed. Sizeable substituent effects are associated with the electronegativity and lone pair of the oxygen nucleus in the hydroxyl and carbonyl systems. In addition, the π-system of the carbonyl group may also be important. Such substituent effects may be as large at ±5 Hz. Since nJCH constants rarely exceed 10 Hz, these effects can produce important deviations in nJCH magnitudes and therefore are essential for applications to stereochemical and conformational analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260321105
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