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  • 1
    Electronic Resource
    Electronic Resource
    Reaktionen der Trialkylsilyl-trifluormethansulfonate, XI. Synthese von Derivaten der α-Ketocarbonsäuren aus 2-O-funktionell substituierten Trimethylsilylketenacetalen (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 607-613 
    Details
    ISSN: 0170-2041
    Keywords: 1,3-Dioxolanes ; 1,3-Oxazolidines ; α-Oxocarboxylic acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Trialkylsilyl Trifluoromethanesulfonates XI.  -  Synthesis of α-Oxocarboxylic Acid Derivatives from 2-O-Functionalized Trimethylsilyl Ketene AcetalsThe cyclic ketene acetals 3, 5 are prepared from the dioxolanone 2 resp. the oxazolidinediones 4 by silylation with trimethylsilyl triflate (1)/triethylamine. In an aldol addition/Peterson olefination reaction catalysed by 1 the ketene acetals 3, 5 yield the (E/Z)-benzylidene derivatives 7, 12, 13 in reaction with aromatic aldehydes 6. In a side reaction the α-(trimethylsilyl)benzylidene derivatives 8 are formed from 3 and 6. Compounds 7 can be hydrolysed to yield α-ketocarboxylic acids 14. The latter are also obtained via β-elimination of trimethylsilanol from 2,3-bis(trimethylsiloxy)carboxylic acid esters 15 with trifluoroacetic acid anhydride/DMAP/pyridine.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1992199201104
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  • 2
    Electronic Resource
    Electronic Resource
    Reaktionen der Trialkylsilyl-trifluormethansulfonate, X. N-(Trifluoracetyl)-α,β-didehydro-α-aminosäureester durch Trimethylsilanol-Eliminierung aus 2-[(Trifluoracetyl)amino]-3-(trimethylsiloxy)carbonsäureestern (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 11-17 
    Details
    ISSN: 0170-2041
    Keywords: α-Amino-β-(trimethylsiloxy)carboxylic acid esters, β-elimination ; α,β-Didehydro α-amino acid esters ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Trialkylsilyl Trifluoromethanesulfonates, X. - N-(Trifluoroacetyl)-α,β-didehydro-α-amino Carboxylic Acid Esters from 2-(Trifluoroacetyl)amino]-3-(trimethylsiloxy)carboxylic Acid Esters by Elimination of Trimethylsilanolα-Amino-β-(trimethylsiloxy)carboxylates 4 are obtained by trimethylsiloxy alkylation of the ketene acetal 1 with aldehydes 2 in the presence of trimethylsilyl triflate (3). β-Elimination of trimethylsilanol from the esters 4 by means of trifluoroacetic acid anhydride (8) or methanesulfonic acid anhydride (15) yields (Z)-didehydro amino acid esters 7. The course of the elimination reaction is studied.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199119910103
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  • 3
    Electronic Resource
    Electronic Resource
    Reaktionen der Trialkylsilyl-trifluormethansulfonate, IX. Elektrophile Silylierung elektronenreicher Alkene (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 745-750 
    Details
    ISSN: 0170-2041
    Keywords: Ketene acetals, 2-(trimethylsilyl)- ; Trialkylsilyl trifluoromethanesulfonates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Trialkylsilyl Trifluoromethanesulfonates, IX.  -  Electrophilic Silylation of Electron-Rich AlkenesKetene O,O-, O,S-, and O,N-acetals 1, 7, and 9 are converted into the C-silylated derivatives 4, 8, and 11, respectively, by reaction with trimethylsilyl triflate (2a)/tertiary amine or sodium hydride. The ambident character of the ketene O,O-acetals 1 in the silylation with 2a is studied.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1990199001140
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  • 4
    Electronic Resource
    Electronic Resource
    Reaktionen der Trialkylsilyl-trifluormethansulfonate, XII. Aldol-Additionsreaktionen mit 2,6-Bis(trimethylsiloxy)thiophen-Synthese bicyclischer γ-Lactone (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 615-620 
    Details
    ISSN: 0170-2041
    Keywords: Thiophenes ; 3,7-Dioxabicyclo[3.3.0]octanes ; Aldol additions ; Lactones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Trialkylsilyl Trifluoromethanesulfonates, XII.  -  Aldol-Type Reactions with 2,6-Bis(trimethylsiloxy)thiophene Synthesis of Bicyclic γ-LactonesIn the presence of trimethylsilyl triflate (2) aromatic aldehydes 4 react with 2,6-bis(trimethylsiloxy)thiophene (3) to yield the 3,4-disubstituted thiosuccinic anhydrides 5. By hydrolysis of the products 5 in the presence of lead acetate the diaryl-substituted cis-bislactones 8 are obtained. Dialkyl-substituted cis-bislactones 10 are formed in a aldol addition of aliphatic aldehydes 9 to 3 catalysed by zinc chloride and subsequent hydrolysis of the intermediates. The synthesis of 3,4-bis(dialkoxyalkyl)thiosuccinic anhydrides 7 is achieved by the reaction of 3 with carboxylic acid orthoesters 6 catalysed by 2.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1992199201105
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