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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 7 (1975), S. 18-22 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 13C magnetic resonance spectra of six diastereomeric mixtures of quaternary ammonium salts were investigated. Assignment of the signals of the non-aromatic carbons and measurement of the non-equivalences allowed the determination of the ratio of isomers in the mixtures. A deshielding β effect and a shielding γ effect for the quaternisation were pointed out.
    Notes: Les spectres de 13C de six couples d'ammoniums quaternaires ont été étudiés. L'attribution des signaux des carbones non-aromatiques et la détermination des non-équivalences ont conduit au dosage des diastéréoisomères ainsi qu'à la mise en évidence d'un effect β déblindant et γ blindant lors de la quaternarisation.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 16 (1981), S. 273-279 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithium and magnesium enolates of an α-sulphinyl ester 83% 13C enriched at C-1 and C-2 are studied by 13C NMR at different temperatures. It is shown that two metaliated species are present in the case of lithium which exchange at -60°C, ΔG≠ -60° = 37.8 KJ mol-1 (9.05 Kcal mol-1) and that there is no rapid exchange between the non-metallated ester and the metallated species (on the NMR time scale). In the case of magnesium, two or three metallated species are formed, according to the temperature which do not exchange up to 0 °C.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 17 (1981), S. 227-231 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon-13 and proton NMR data of macrocyclic diaromatic dilactones are presented. The observed behaviour of the spectra as a function of temperature shows that the energy barrier for the re-orientation of the side chains is lower than 49 kJ mol-1 (12 kcal mol-1) and that the energy barrier for the rotation of the aromatic rings is larger than 99 kJ mol-1 (24 kcal mol-1). Hence, chiral substituted dilactones of this type will be resolvable, and the enantiomers can be easily handled at room temperature.
    Additional Material: 1 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 17 (1981), S. 303-305 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two possible conformations of 13-R-substituted oxyprotoberberines are enantiomeric. The racemization barriers are determined for three of these compounds (R=OMe, OCOMe, OCOPh) using variable temperature 1H NMR. It was found that ΔG203
    Additional Material: 1 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 10 (1977), S. 105-111 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbon-13 chemical shifts (substituents effects, variations of shielding and deshielding related to the magnitude of n.π or π.π interactions) not only confirm the non-planar conformation of ketimines of the benzalaniline type, but provide torsional angles of the aromatic rings. Carbon-13 chemical shifts of dibenzo[b,f] diazocines[1,4] confirm the tub-like conformations and the presence of n.π and π.π interactions.
    Notes: L'étude des déplacements chimiques 13C (effets de substituants, variation du blindage ou du déblindage dǔ à l'intervention d'interactions n.π ou π.π) confirme la structure non plane des cétimines diàromatiques étudiées et permet d'évaluer les angles de torsion des cycles aromatiques hors du plan de la double liaison C=N. L'étude des déplacements chimiques 13C de dibenzo[b,f] diazocines-1,4 confirme la structure ‘tub’ et la présence d'interactions n.π et π.π.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 10 (1977), S. 235-237 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Torsional angles in some mono-substituted conjugated benzenes were determined from the chemical shift of the para carbons. Similar results were obtained from ketones and imines, and the torsional angles increase, as expected, with steric hindrance. It is possible to assign a syn or anti stereochemistry for the imines from the value of the torsional angle.
    Additional Material: 3 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 14 (1980), S. 426-430 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that 13C NMR is not suitable for determining the conformation of the Cr(CO)3 group in monosubstituted chromium tricarbonyl complexes. However,. 1H NMR can be used for such determinations if one takes substituent effects into account, whn necessary, and an appropriate relationship is proposed. The populations, xA, of the eclipsed conformer so obtained for various substituents increase with the π donor ability of the substituent. These results are consistent with X-ray results and with Carter and Hoffmann's models.
    Additional Material: 7 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 16 (1981), S. 44-46 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 250 MHz 1H NMR of two monosubstituted [2.2]paracyclophanes shows that whether the substituent is an electron releasing group, OMe, or a withdrawing group, CO2Me, the transannular effect is deshielding. 62.86 MHz 13C NMR shows that among the six transannular effects, only one has a sign which changes with the nature of the substituent (-4.6 ppm for OMe but +3.3 ppm for CO2Me).
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 21 (1983), S. 367-370 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The assignment of meso and dl diastereomers is carried out by NMR analysis of the signals due to the methylene protons in two simple cases, namely, dimethyl α,α′-dibromopimelate (as an acyclic compound) and N-benzyl-2,6-dicarbomethoxypiperidine (as a cyclic compound). In the case of the heterocyclic compound, an nσσ* hyperconjugative interaction between the CH bond α to the heteroatom and the lone pair of the heteroatom can be used, and leads to the same assignment.
    Additional Material: 4 Ill.
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  • 10
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Phosphazene base ; Pyridyl epoxide ; Furyl epoxide ; Pyridyl alcohol ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---trans-1-(2-Pyridyl)-, trans-1-(3-pyridyl)-, trans-1(2-furyl)-, and trans-1(3-furyl)-2-phenyl epoxides with enantiomeric purities ranging from 96.8 to 99.8% [in favor of the (+, EtOH)-isomer] are obtained in two steps from pure (R,R,R)-oxathiane which is recovered (85-90%) and reused. The chiral bidentate ligand 2-phenyl-(S)-1-(2-pyridyl)ethanol with 99.6% ee was obtained in three steps and 67% overall isolated yield.
    Additional Material: 1 Ill.
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