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  • 1
    Electronic Resource
    Electronic Resource
    Tautomerism and the Mills-Nixon-like effect in pyrazoles (1997)
    Springer
    Structural chemistry 8 (1997), S. 189-195 
    Details
    ISSN: 1572-9001
    Keywords: Mills-Nixon-like effect ; AM1 calculations ; ab initio calculations ; annular tautomerism ; NH-pyrazoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Theoretical calculations on a wide variety of NH-pyrazoles clearly show a relationship between ring strain and annular tautomerism, i.e., the most stable tautomer is that having the largest singleond character in the C3-C4 bond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263506
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  • 2
    Electronic Resource
    Electronic Resource
    Novel (E)- and (Z)-2-Styrylchromones from (E, E)-2′-Hydroxycinnamylideneacetophenones - Xanthones from Daylight Photooxidative Cyclization of (E)-2-Styrylchromones (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2031-2038 
    Details
    ISSN: 1434-193X
    Keywords: (E,E)-2′-Hydroxycinnamylideneacetophenones ; (E)- and (Z)-2-Styrylchromones ; Xanthones ; Oxidative cyclizations ; Configuration determination ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidative cyclization of (E,E)-2′-hydroxycinnamylideneacetophenones 1a-e, and (E, E)-2′-benzyloxy-6′-hydroxycinnamylideneacetophenones 1i-l with DMSO/iodine, gave (E)-2-styrylchromones 3a-e,i-l. However, in the case of (E, E)-γ-alkyl-2′-hydroxycinnamylideneacetophenones 1f-h, (E)- and (Z)-2-styrylchromones 3f-h and 4f-h were obtained. The stereochemistry of the (E,E)-cinnamylideneacetophenones 1 and (E)- and (Z)-2-styrylchromones 3 and 4 was established by NOE experiments. The induced daylight photooxidative cyclization of some (E)-2-styrylchromones 3a,f-h gave 12H-benzo[a]xanthene-12-ones 6a,f-h.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidation of 4-Alkyl-2′-Hydroxy-2-cinnamylideneacetophenones with Thallium(III) Trinitrate: A New Synthesis of (E)-3-Styrylchromones (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2065-2068 
    Details
    ISSN: 0947-3440
    Keywords: Thallium(III) trinitrate ; Oxidative rearrangement ; 2′-Hydroxy-2-cinnamylideneacetophenones ; (E)-3-Styrylchromones ; Configuration determination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidative rearrangement of (E,E)-4-alkyl-2′-hydroxy-2-cinnamylideneacetophenones 4, obtained by base-catalysed aldol reaction of 2′-hydroxyacetophenone and cinnamaldehydes with thallium(III) trinitrate, gave the corresponding 3-alkyl-4-aryl-1-(2′-hydroxyphenyl)-2-(dimethoxymethyl)-3-buten-1-ones. The cyclization of these acetal intermediates with hydrochloric acid gave (E)-3-styrylchromones 5. The stereochemistry of the 4-alkyl-2′-hydroxy-2-cinnamylidene-acetophenones 4 and 3-styrylchromones 5 double bonds was established by NOE experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971009
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  • 4
    Electronic Resource
    Electronic Resource
    On the Tautomerism of 2-Phenacyl-4-pyrimidinones and Related Compounds (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 919-924 
    Details
    ISSN: 0009-2940
    Keywords: Pyrimidinones ; Tautomerism ; AM1 calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zur Tautomerie von 2-Phenacyl-4-pyrimidinonen und verwandten Verbindungen3-Methyl-2-phenacyl-4-pyrimidinone 1, 2 werden durch Sulfidkontraktion synthetisiert. Aufgrund der NMR-Daten existieren die Verbindungen ausschließlich in der Benzoylmethylen-Form, sowohl in Lösung als auch als Festkörper. Diese Ergebnisse werden durch AM1-Berechnungen für die Stammverbindung bestätigt. Die Untersuchung des Tautomeren-Gleichgewichts mittels dieser semiempirischen Methode wurde auf andere Fälle von Enaminoketon/Enolimin-Tautomerie erweitert.
    Notes: 3-Methyl-2-phenacyl-4-pyrimidinones 1, 2 have been synthesized using the sulfide contraction. According to the NMR data, the compounds 1, 2 exist exclusively as the benzoylmethylene tautomers a both in solution and in the solid state. AM1 calculations of the parent system are in agreement with the experimental observations. The study of the tautomeric equilibrium by this semiempirical method has been extended to other cases of enamino-ketone/enolimine tautomerism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220521
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