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  • Organic Chemistry  (2)
  • Aziridines, regioselectivity of ring opening
  • Inorganic Chemistry
  • 1970-1974  (2)
  • 1971  (2)
Collection
Keywords
  • Organic Chemistry  (2)
  • Aziridines, regioselectivity of ring opening
  • Inorganic Chemistry
  • Chemistry  (2)
Publisher
Years
  • 1970-1974  (2)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 748 (1971), S. 143-153 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nitrones, II1). 2,3,4-Substituted 5-Isoxazolidinones from Aldonitrones and CH-Acidic CompoundsDialkyl malonates and C-aryl-N-methylnitrones 1 as well as 3,4-dihydroisoquinoline N-oxide in presence of sodium alkoxide yield the alkyl 5-isoxazolidinone-4-carboxylates 4,6, and 7; the compounds 4 are exclusively trans-substituted with exception of 4c. Malonic acid diamide reacts in the same way to give the corresponding 5-isoxazolidinone-4-carboxamide 8. C-Styryl-N-methylnitrone and dimethyl malonate yield a mixture in which the corresponding isoxazolidinone 5 is spectroscopically recognized. Analogously, ethyl acetoacetate gives the corresponding trans-substituted 4-acetylisoxazolidinone derivative 9. Under aprotic conditions, even methyl phenylacetate reacts with a nitrone furnishing the 3,4-diaryl substituted isoxazolidinone 10.
    Notes: C-Aryl-N-methyl-nitrone 1 sowie 3.4-Dihydro-isochinolin-N-oxid ergeben mit Malonsäurediestern und Natriumalkoxid die Isoxazolidinon-(5)-carbonsäure-(4)-ester 4,6 und 7. Die Verbindungen 4 sind, mit Ausnahme von 4c, im Isoxazolidinon-Ring ausschließlich trans-substituiert. Analog reagiert Malonsäurediamid unter Bildung des entsprechenden Isoxazolidinon-(5)-carbonsäure-(4)-amids 8. C-Styryl-N-methyl-nitron liefert mit Malonsäuredimethylester ein Gemisch, in dem das Isoxazolidinon 5 spektroskopisch zu erkennen ist. Acetessigester gibt entsprechend das ebenfalls trans-substituierte 4-Acetyl-isoxazolidinon-Derivat 9. Unter aprotischen Bedingungen reagiert auch Phenylessigester mit einem Nitron, wobei das 3.4-Diaryl-substituierte Isoxazolidinon 10 entsteht.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 749 (1971), S. 146-152 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nitrones, III. The Reformatzky Reaction with NitronesThe Reformatzky reaction may be applied to nitrones as carbonyl analogues when tetrahydrofuran is used as solvent and the reaction temperature is controlled. The N-methyl-C-aryl-aldonitrones 1 react with zinc and the ethyl α-bromo-alkanecarboxylates 2 to yield the corresponding 2-methyl-3-aryl-5-isoxazolidinones carrying 0, 1 or 2 methyl groups in position 4 depending on the ester used. Analogously 3,4-dihydroisoquinoline-N-oxide (5) is converted to the unstable compound 6. m- and p-Nitro-benzaldehyde-N-methylnitrone do not react. Those nitrone substituents which increase the electronic charge at the nitrone O-atom favor HBr elimination as competing reaction which completely dominates in the case of p-dimethylaminobenzaldehyde-N-methylnitrone. The 2,4-dimethyl-3-aryl-5-isoxazolidinones (4d, e) are obtained as mixtures of the geometrical isomers.
    Notes: Die Reformatzky-Reaktion läßt sich in Tetrahydrofuran als Lösungsmittel bei geeigneter Temperaturführung auf die Carbonyl-analogen Nitrone übertragen. Mit Hilfe von Zink und α-Brom-alkancarbonsäureestern 2 erhält man aus den N-Methyl-C-aryl-aldonitronen 1 die 2-Methyl-3-aryl-isoxazolidinone-(5) 4, welche je nach verwendetem Ester in 4-Stellung 0, 1 oder 2 Methylgruppen tragen. Analog reagiert 3.4-Dihydro-isochinolin-N-oxid (5) zur instabilen Verbindung 6. m- und p-Nitro-benzaldehyd-N-methyl-nitron setzen sich nicht um. Substituenten, welche die Elektronendichte am Nitron-O-Atom erhöhen, begünstigen als Konkurrenzreaktion die HBr-Eliminierung, die im Falle des p-Dimethylamino-benzaldehyd-N-methyl-nitrons die Reformatzky-Reaktion völlig zurückdrängt. Die 2.4-Dimethyl-3-arylisoxazolidinone-(5) (4d, e) werden als cis/trans-Isomerengemische erhalten.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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