Search results for "Fries rearrangement"
showing 10 items of 10 documents
Characterization of some isomeric benzophenones by their mass spectra
1979
Benzophenones have been described to undergo characteristic α-cleavage and rearrangement processes upon mass spectrometric fragmentation. Recently two series of new and isomeric benzophenones have been prepared from phenylbenzoates by Fries rearrangement or directly by Friedel Crafts acylation. It is shown that the above mentioned diagnostic fragmentation processes can be used to characterize the resulting isomeric ortho or para hydroxy and ortho or para methoxy benzophenones unambigously.
Untersuchungen zur friesschen verschiebung an hydroxybenzylphenol-derivaten
1974
An den Acetaten 2a–c, 3b, 4b und 4d von sechs Hydroxybenzylphenol-Derivaten wurde die Friessche Verschiebung mit AlCl3 als Katalysator in Nitrobenzol bei Temperaturen zwischen 40 und 70°C durchgefuhrt. Neben den zu erwartenden Hauptprodukten der Friesschen Verschiebung konnte durch Saulenchromatographie eine Reihe von Zwischen- und Nebenprodukten isoliert werden. Daraus ging hervor, das wahrscheinlich eine teilweise Verseifung der Acetate als Nebenreaktion stattfindet. Eine Wanderung der Acetylgruppe an den benachbarten Phenolbaustein des gleichen Molekuls konnte nicht beobachtet werden. Samtliche Verbindungen, einschlieslich der Ausgangsprodukte, wurden durch ihre IR- und 1H-NMR-Spektren c…
Untersuchungen zurFriesschen Verschiebung von Estern derortho- undpara-Methoxybenzoes�ure
1979
TheFries rearrangement of different methoxy benzoates has been investigated. Frompara-methoxy benzoates the corresponding hydroxy-4′-methoxy benzophenones could be obtained in good yields by treatment withLewis acids (especially TiCl4) in nitromethane at 20°C (4-hydroxy derivatives) or without solvent at 120°C (2-hydroxy derivatives). Under the same conditions only demethylation occurs withortho-methoxy benzoates leading to the corresponding salicylates. Small amounts of hydroxy-2′-methoxy benzophenones were obtained by treatment with polyphosphoric acid.
A contribution to the preparation of phenolic polynuclear compounds with sulfonyl bridges
1964
For the preparation of phenolic di- and tricyclic compounds with sulfonyl bridges the Fries rearrangement is suitable, and for the corresponding products with three and four benzene rings the Friedel-Crafts reaction may be used. The exchange of sulfonyl bridges for methylene bridges produces a marked increase in the melting point.
Photochemical versus aluminium chloride-catalyzed fries rearrangement of aryl hydrogen succinates. synthesis of 2(3H)-furanones
1989
The photochemical and aluminium chloride-catalyzed Fries rearrangement of a series of aryl hydrogen succinates3 a–f to the corresponding 4-oxoacids1 a–f are compared. Both approaches are complementary: the photochemical process is more general and becomes the method of choice for the succinoylation of phenols supporting alkoxy or hydroxy substituents, while the classical rearrangement is superior in the presence of alkyl or halogen substituents. These results are applied to the preparation of the 2(3H)-furanones2 a–f.
Eine oligomeranaloge friessche umlagerung oligomerer 2-acetoxy-1,3-phenylenmethylene
1979
α-Hydro-ω-hydroxypoly(5-chloro-2-hydroxy-1,3-phenylenemethylene)s (1a, b), the oligomeric condensation products from 4-chloro-2,6-bis(hydroxymethyl)phenol and 4-chlorophenol with hydrochloric acid in 1,4-dioxane, could be completely dehalogenated at room temperature and atmospheric pressure with hydrogene/Raney-Ni. The resulting oligomers 2a, b were esterified with acetic anhydride, and the esters 3a, b were subjected to a oligomer analogous Fries rearrangement to form the linear α-hydro-ω-hydroxypoly(5-acetyl-2-hydroxy-1,3-phenylenemethylene)s 4a and 4b. The characterization of the products was mainly done by spectroscopic methods.
Influence of enol acetylation on the photo-fries rearrangement of anortho-acylaryl benzoate
1982
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. Einflus der Enol-Acetylierung auf die Photo-Fries-Umlagerung eines Benzoesaure-ortho-acylarylesters Das Enolacetat 1b erleidet bei Bestrahlung Spaltung der Benzoyl-Sauerstoff-Bindung, wobei ei…
Zur herstellung molekulareinheitlicher, über schwefelhaltige brücken verbundener, phenolischer zweikernverbindungen
1963
Phenole lassen sich mit Thionylchlorid mittels Aluminiumchlorid in hohen Ausbeuten zu molekulareinheitlichen Sulfoxyden kondensieren, die sich im praparativen Masstab einerseits zu Sulfiden reduzieren und andererseits zu Sulfonen oxydieren lassen. Die Sulfone konnen auch in guten Ausbeuten mittels Aluminiumchlorid durch Kondensation von Phenolathersulfochloriden mit Phenolathern und durch FRIESsche Verschiebung entsprechender Sulfonsaureester erhalten werden. Phenols can be condensed with thionylchloride using aluminium chloride as catalyst in good yields to molecularly defined sulfoxides, which can be preparatively reduced to sulphides or oxidised to sulphones. The sulphones were also obta…
Darstellung und spektroskopische Analyse von Oligo{[4-(1,1,3,3-tetramethylbutyl) (bzw. 4-octyl)2-hydroxy-1,3-phenylen]methylen}en und ihrer Ausgangsv…
1978
4-(1,1,3,3-Tetramethylbutyl)phenol und 4-Octylphenol, erhalten durch Friessche Verschiebung der entsprechenden Phenylester und anschliesende Reduktion der Carbonylgruppe, wurden in ortho-Stellung monobromiert und mit Formaldehyd hydroxymethyliert. Aus diesen Verbindungen konnten sechs 2,2′-Methylendiphenole (2a–f) sowie sieben 2,6-Bis(2-hydroxybenzyl)phenole (3a–g) dargestellt werden, die in 4-Stellung zu den phenolischen Hydroxygruppen Methyl-, 1,1,3,3-Tetramethylbutyl- und Octyl-Substituenten in verschiedenen Verhaltnissen enthalten. Die IR- und 1H-NMR-spektroskpischen Analysen bestatigten die angegebenen Strukturen der dargestellten phenolischen Mehrkernverbindungen. 4-(1,1,3,3-Tetrameth…
Friessche Verschiebung vonortho- undpara-Methoxyphenylacetaten. Die Bildung von Ketoestern
1980
During theFries rearrangement ofo- andp-methoxy phenyl acetates with AlCl3 in nitromethane at 20°C substitution occurs mainly in thep-position of the phenolic residue to yieldp-acylphenols. Larger quantities ofo-acylphenols are obtained only, if thisp-position is already substituted. Witho-methoxy phenyl acetates the substitution of the acid residue to yield ketoesters is observed as a side reaction. Those ketoesters are obtained as main products if TiCl4 is taken as a catalyst.