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  • 1
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Trialkylsilyl Trifluoromethanesulfonates, VI. - Synthesis of 2-Heterosubstituted O-Alkyl-O-(trimethylsilyl)ketene Acetals and 2-(Trimethylsilyl)carboxylatesOrganooxy- and (alkylthio)ethanoic acid esters 2 are silylated by trimethylsilyl triflate (1) in the presence of triethylamine to yield mixtures of ketene acetals 3 and 2-(trimethylsilyl)ethanoates 4. The product distributions 3/4 are governed by the ester groups and the substituents in α position. Cyclic derivatives of 2-hydroxycarboxylic acids 7,9 are silylated by 1/triethylamine to give the ketene acetals 8, 10. From N-protected glycine methyl esters 11, 12 the ketene acetals 13, 15 are obtained in the reaction with 1/triethylamine.
    Notes: Durch Silylierung von Organooxy- und (Alkylthio)essigestern 2 mit Trimethylsilyltriflat (1) in Gegenwart von Triethylamin erhält man Gemische aus Ketenacetalen 3 und 2-(Trimethylsilyl)essigestern 4. Die Produktverteilung 3/4 wird durch die Estergruppen sowie die α-Substituenten in den Estern 2 gesteuert. Cyclische Derivate der 2-Hydroxycarbonsäuren 7, 9 werden durch 1/Triethylamin in die Ketenacetale 8, 10 übergeführt. N-geschützte Glycin-methylester 11, 12 ergeben bei Umsetzung mit 1/Triethylamin die Ketenacetale 13, 15.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 693-699 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Trialkylsilyl Trifluoromethanesulfonates VII. - α-Trimethylsiloxycarboxylation by Tris(trimethylsiloxy)etheneIn the presence of trimethylsilyl triflate (1), acetals and orthocarboxylic acid esters 3 react with tris(trimethylsiloxy)ethene 2 to yield 3-alkoxy- and 3,3-dialkoxy-2-(trimethylsiloxy)carboxylates 4. From carbonyl compounds 6 and the ketene acetal 2 2,3-bis(trimethylsiloxy)carboxylates 7 are obtained. Silylcarboxylates 15, 16 are formed by addition of the compound 2 to α,β-unsaturated carbonyl compounds 14 under catalysis of the Lewis acid 1. Alkylation reagents 17, 18 react with the ketene acetal 2 to give 2-(trimethylsiloxy)carboxylates 19, 20.
    Notes: In Gegenwart von Trimethylsilyltriflat (1) reagieren Acetale und Orthoester 3 mit Tris(trimethylsiloxy)ethen (2) zu 3-Alkoxy- und 3,3-Dialkoxy-2-(trimethylsiloxy)alkansäureestern 4. Aus Carbonylverbindungen 6 und dem Ketenacetal 2 erhält man die 2,3-Bis(trimethylsiloxy)carbonsäureester 7. Die Addition von 2 an α,β-ungesättigte Carbonylverbindungen 14 zu den Carbonsäuresilylestern 15, 16 wird durch die Lewis-Säure 1 katalysiert. Alkylierungsreagenzien 17, 18 setzen sich mit dem Ketenacetal 2 zu den 2-(Trimethylsiloxy)carbonsäureestern 19, 20 um.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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