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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 297-303 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acylation of 2,5-dihydro-2,2-dimethyl-1,3-thiazoles leads to 3-acyl-2,3-dihydro-2,2-dimethyl-1,3-thiazoles as potential starting materials for the total synthesis of racemic cephalosporins.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 819-825 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Halogenation of Et3N, (i-Pr)2EtN, and N-ethylmorpholine or of enamines with dichlorotriphenylphosphorane gives in up to 75% yield the corresponding [2-(dialkylamino)vinyl]triphenylphosphonium chlorides, which can be readily converted into the corresponding stable crystalline tetraphenylborates (Schemes 2 and 3).
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aus den Blättern von Glycosmis arborea (Rutaceae) wurden zwei neue epimere pentacyclische Triterpene, Arborinol und Isoarborinol, isoliert. Durch chemischen Abbau und Anwendung physikalischer Methoden, insbesondere der kernmagnetischen Resonanz (NMR), der optischen Rotationsdispersion und der Massenspektroskopie konnte die Struktur der Ringe A, B und C der Arborinole aufgeklärt und die Existenz von zwei sekundären Methylgruppen im Rest des Moleküls nachgewiesen werden. Für Arborinol und Isoarborinol wird deshalb die Struktur von 3-Hydroxy-Δ9(11)-13β.14α-dimethyl-pentacyclischen Triterpenen (I bzw. III) angenommen; sie stellen damit einen neuen Triterpen-Typus dar.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1974 (1974), S. 821-834 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Amide AcetalsReactions of amide acetals, e. g. ketalisation of carbonyl compounds, esterification of carboxylic acids, formation of phenolic ethers and inversion of 3-hydroxy steroids are described and their mechanisms and side reactions discussed. - The dimethyl acetal of N-formyl- pyrrolidine esterifies 4-nitrobenzoic acid not only faster but, owing to diminished side reactions, also in higher yields compared to the commonly used dimethyl acetal of dimethyl- formamide.
    Notes: Reaktionen von Amidacetalen wie Ketalisierung von Carbonylverbindungen, Veresterung von Carbonsäuren, Bildung von Phenoläthern sowie Konfigurationsumkehr von 3-Hydroxysteroiden werden beschrieben sowie ihre Mechanismen und Nebenreaktionen diskutiert. - Das Dimethylacetal des N-Formylpyrrolidins verestert 4-Nitrobenzoesäure nicht nur schneller, sondern wegen der verminderten Nebenreaktionen auch in höheren Ausbeuten als das gewöhnlich benutzte Dimethylacetal des Dimethylformamids.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleoside Syntheses, XVIII.  -  Amination of Heterocycles, II.  -  Facile Synthesis of N6-Substituted Adenosines and Adenines and Their 2-Amino- and 2-Hydroxy DerivativesHerrn Prof. Dr. H. Gibian zum 60. Geburtstag gewidmet.Reaction of inosine, guanosine or xanthosine as well as their 5′-phosphates with hexamethyl-disilazane and ammonia, or primary or secondary amines in the presence of Lewis acids, such as (NH4)2SO4, (CH3)3Si—O—SO2CF3, p-toluenesulfonic acid hydrate or Hg(I1)-salts, gives the corresponding N6-substituted adenosines or 2-amino- or 2-hydroxyadenosines in high yields. Hypoxanthine or guanosine are converted analogously into the corresponding N6-substituted adenines or 2-aminoadenines.
    Notes: Reaktion von Inosin, Guanosin, Xanthosin sowie ihrer 5′-Phosphate mit Hexamethyldisilazan und Ammoniak, primaren oder sekundaren Aminen in Gegenwart von Lewissäuren wie (NH4)2SO4, (CH3)3Si—0—SO2CF3, p-Toluolsulfonsäurehydrat und Hg(I1)-salzen ergibt in hohen Ausbeuten die entsprechenden N6-substituierten Adenosine bzw. 2-Amino- oder 2-Hydroxyadenosine. Analog lassen sich Hypoxanthin und Guanosin in die entsprechenden N6-substituierten Adenine bzw. 2-Aminoadenine umwandeln.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 1438-1447 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosid-Synthesen, XXI.  -  Synthese von 5-Methylaminomethyl-2-thiouridin, eines seltenen Nucleosids aus t-RNSDie Synthese von 5-Methylaminomethyl-2-thiouridin (1), eines seltenen Nucleosids aus t-RNS, ausgehend von den entsprechenden 2-Thiouracil- und Ribose-Derivaten wird beschrieben. Während der Silyl-Hilbert-Johnson-Nucleosid-Synthese in Gegenwart von Silberperchlorat wird die tert-Butoxycarbonyl-Aminoschutzgruppe (Boc) im 2-Thiouracil-Teil abgespalten. Diese Spaltung wird durch intermediär gebildetes Trimethylsilylperchlorat bewirkt. Präparative Anwendungen dieser neuen Art von Lewis-Säuren werden angegeben.
    Notes: The synthesis of 5-methylaminomethyl-2-thiouridine (1), a rare nucleoside from t-RNA, starting from the appropriate 2-thiouracil and ribose derivatives is described. During the silyl Hilbert-Johnson nucleoside synthesis with silver perchlorate the tert-butoxycarbonyl (Boc) aminoprotecting group in the 2-thiouracil moiety is removed. This cleavage is due to the intermediate formation of trimethylsilyl perchlorate. Preparative applications of this new type of Lewis acids are mentioned.
    Type of Medium: Electronic Resource
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