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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1497-1512 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 21,2). N-Acetyl α,β-Didehydro α-Amino Acid Esters from α-Azidocarboxylic Acid Esters and Acetic Anhydride by Nitrogen Elimination with Rhenium Catalystsα-Azidocarboxylic acid esters 2 react with acetic anhydride in presence of catalytic amounts of rhenium heptasulfide and - if necessary - by addition of hydrochloric acid to give N-acetyl 3 or/and N,N-diacetyl-α,β-didehydro-α-amino acids esters 4 in very good yields. Exclusively monoacetylated products 3 are formed if water ist added before work up.
    Notes: Beim Erwärmen von α-Azidocarbonsäureestern 2 in Acetanhydrid/Essigsäure in Gegenwart katalytischer Mengen Rheniumheptasulfid und gegebenenfalls unter Zugabe von Chlorwasserstoff entstehen in sehr guten Ausbeuten N-Acetyl- 3 und/oder N,N-Diacetyl-α-β-didehydro-α-amino-säureester 4. Durch Zugabe von Wasser vor der Aufarbeitung erfolgt partielle Deacetylierung unter ausschließlicher Bildung der N-Monoacetylverbindungen 3.
    Additional Material: 7 Tab.
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  • 2
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 31). N-Acetylated α-β-Didehydro α-Amino Acid Derivatives by Nitrogen Elimination from α-Azido-carboxylic Acid Amides and α-Azido-ω-aminocarboxylic Acid Lactams with Rhenium Catalystsα-Azidocarboxylic acid amides 2 and α-azido-ω-aminocarboxylic acid lactams 6, respectively, react with acetic anhydride in the presence of rhenium catalysts by nitrogen eliminations to give N-acetyl- 7 and N,N-diacetyl-α,β-didehydro-α-amino acid amides 8, α-acetylamino- 11 and α-diacetylamino-α,β-didehydro-ω-aminocarboxylic acid lactams 12, respectively. Reactions of the educts 6c, d - with a ring size 7 or 8 - additionally lead to the oxazoloazepine 14c and the oxazoloazocine 14d, respectively.
    Notes: Bei der Umsetzung von α-Azidocarbonsäureamiden 2 mit Acetanhydrid in Gegenwart von Rheniumkatalysatoren entstehen unter Stickstoffabspaltung N-Acetyl- 7 und N,N-Diacetyl-α,β-didehydro-α-aminosäureamide 8, bei der von α-Azido-ω-aminocarbonsäurelactamen 6 α-Acetyl-amino- 11 und α-Diacetylamino-α,β-didehydro-ω-aminocarbonsäurelactamen 12, wobei sich aus den Verbindungen 6c, d, mit der Ringgliederzahl 7 bzw. 8 außerdem noch das Oxazoloazepin 14c bzw. das Oxazoloazocin 14d bilden.
    Additional Material: 3 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 2209-2223 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Amino Acids, 12. - Syntheses of DL-Cysteines from Acrylic Acid DerivativesThe addition of sulfenyl chlorides 1 to 2-alkenoic acid esters 2 gives mixtures of 2(3)-chloro-3(2)-thioalkenoic acid esters 3/4, whereas the addition of thiols 7 to methyl 2-chloro-2-propenoate (6) results in the formation of methyl 2-chloro-3-thiopropanoates 3 only. The dependence of the isomerization of 3 to 4 on the reaction conditions was investigated; at higher temperatures the formation of 4 is especially favored. At temperatures below 55°C the 2-azido compounds 8 are obtained without isomerization from 3 by reaction with sodium azide in the presence of a PT catalyst. Cysteine derivatives 9 or 10, resp., are obtained by hydrogenation of 8 with H2S/pyridine/H2O or with H2/Re2S; the overall yields of 9 or 10, resp., starting from 6 are as high as 70% DL-Cysteine is obtained in good overall yields as hydrochloride hydrate 16 by HCl-catalyzed hydrolysis of the 2-thiazolines 15a · HCl and 15e, which are prepared by HCl-catalyzed addition of thioacetamide (11a) to α-chloroacrylic acid (12) or the amide 13 and consecutive ring closure.
    Notes: Die Addition von Sulfenylchloriden 1 an 2-Alkensäureester 2 führt zu Isomerengemischen aus 2(3)-Chlor-3(2)-thioalkansäureestern 3/4, dagegen ergibt die Addition von Thiolen 7 and 2-Chlorpropensäure-methylester (6) isomerenreine 2-Chlor-3-thiopropansäure-methylester 3. Die Isomerisierung von 3 zu 4 in Abhängigkeit von den Reaktionsbedingungen wird untersucht; sie erfolgt besonders leicht bei höheren Temperaturen. Aus 3 werden mit Natriumazid in Gegenwart von PT-Katalysatoren und Temperaturen unterhalb 55°C die isomerenreinen 2-Azido-Verbindungen 8 erhalten, die mit H2S/Pyridin/Wasser oder durch Hydrierung mit Re2S7 als Katalysator die entsprechenden S-substituierten Cystein-Derivate 9 bzw. 10 mit Ausbeuten bis zu 70% über alle Reaktionsstufen ergeben. DL-Cystein ist als Hydrochlorid-Hydrat 16 durch säurekatalysierte Hydrolyse der 2-Thiazoline 15a · HCl und 15e, die durch HCl-katalysierte Addition von Thioacetamid (11b) an α-Chloracrylsäure (12) bzw. deren Amid 13 und anschließende basische Cyclisierung erhalten werden, auf einfache Weise mit guten Gesamtausbeuten zugänglich.
    Additional Material: 10 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4869-4876 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Decomposition of 2-Azido Ketones to 2-(Acetylamino)-2-alken-1-ones by Perrhenate CatalysisThe thermally induced elimination of nitrogen from cyclic and acyclic 2-azido ketones 2 is accelerated by catalytic amounts of perrhenate. In acetic anhydride - if necessary in the presence of small amounts of a mineral acid - 2-(acetylamino)-2-alken-1-ones 3 are formed in good yields. The decomposition rates of the catalysed and the uncatalysed thermolysis are compared.
    Notes: Die thermische Stickstoffabspaltung aus cyclischen und acyclischen 2-Azidoketonen 2 wird durch katalytische Mengen Perrhenat beschleunigt. In Acetanhydrid - gegebenenfalls unter Zusatz geringer Mengen Mineralsäure - entstehen dabei 2-(Acetylamino)-2-alken-1-one 3 in guten Ausbeuten. Die Zersetzungsgeschwindigkeit von katalysierter und nicht katalysierter Thermolyse wird vergleichend untersucht.
    Additional Material: 2 Tab.
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  • 5
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 21 (1982), S. 203-203 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 7
    Publication Date: 1985-01-01
    Print ISSN: 0040-4039
    Electronic ISSN: 1873-3581
    Topics: Chemistry and Pharmacology
    Published by Elsevier
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