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  • 1
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In constrast with recent molecular orbital calculations on the decarboxylation of O-protonated 2-oxetanone, this experimental work indicates that no decarboxylation of this cation occurs in sulphuric acid solution up to 150°C, but instead a clean isomerization to protonated acrylic acid takes place. Parallel theoretical work shows that the gas-phase model is too crude to account successfully for the experimental facts obtained in acidic media. However, the latter are well reproduced when the effect of the solvent is taken into account. The present findings do not necessarily invalidate the reaction mechanism currently accepted to explain the rate enhancement and change of stereochemistry accompanying the decarboxylation of 3,4-disubstituted 2-oxetanones under acid catalysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Einfluß der Enol-Acetylierung auf die Photo-Fries-Umlagerung eines Benzoesäure-ortho-acylarylestersDas Enolacetat 1b erleidet bei Bestrahlung Spaltung der Benzoyl-Sauerstoff-Bindung, wobei eine Mischung der Benzophenone 4 und 5 resultiert. Die primär entstehenden Photo-Fries-Produkte 2 und 3 konnten infolge einer schnellen intramolekularen Umacetylierung nicht isoliert werden. Das Acetophenon 6 lagert sich unter den gleichen experimentellen Bedingungen zu den Benzophenonen 7 und 8 um, jedoch sind die Ausbeuten bemerkenswert niedriger als im obigen Fall. Die Verbindungen 7 und 8 werden durch Acetanhydrid in Gegenwart von Pyridin in die jeweiligen Essigsäureester 4 und 5 übergeführt.
    Notes: The enol acetate 1b undergoes benzoyl-oxygen bond rupture upon irradiation, giving a mixture of benzophenones 4 and 5. The primary photo-Fries products 2 and 3 could not be isolated, due to a rapid intramolecular transacetylation. The acetophenone 6 rearranges to give the benzophenones 7 and 8 under the same conditions, but the yields are significantly lower than in the former case. Compounds 7 and 8 are separately correlated with 4 and 5 by treatment with acetic anhydride in the presence of pyridine.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 589-598 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photolyse von Enolacetaten und α-Bromderivaten von o-(Acyloxy)acetophenonenUV-Bestrahlung der Enolacetate 3a - g in Benzol liefert o-(Acetoxy)acetophenone 2 und 2-Methyl-chromone 4 als Hauptprodukte. Unter den gleichen experimentellen Bedingungen bleiben die Dimethylderivate 3h und 3i unverändert. Das α-Bromketon 5a liefert in Abhängigkeit von den Bestrahlungsbedingungen Mischungen aus o-(Acetoxy)acetophenon (2a), dem Diketon 6 und/oder α-Acetoxy-o-hydroxyacetophenon (7). Die Ähnlichkeiten und Unterschiede zwischen beiden Reihen von Experimenten sowie mechanistische Überlegungen werden diskutiert.
    Notes: UV irradiation of enol acetates 3a - g in benzene gives mainly o-(acetoxy)acetophenones 2 and 2-methylchromones 4. Under the same conditions, the dimethyl derivatives 3h and 3i remain unaffected. The α-bromo ketone 5a gives rise to mixtures of o-(acetoxy)acetophenone (2a), the diketone 6, and/or α-acetoxy-o-hydroxyacetophenone (7), depending on the irradiation conditions. The similarities and differences between the two series of experiments, as well as their possible mechanistic implications, are discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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