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  • 1
    ISSN: 0947-3440
    Keywords: Domino reaction ; Functionalized cyclopentanes, -hexanes and -heptanes ; Tetrahydrofurans ; Oxetanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Functionalized cyclopentanes, -hexanes and -heptanes are obtained by addition of lithiated silyldithioacetals 7 to epoxyhomoallyl tosylates 4-6, The reaction involves a cascade of epoxide ring opening, of Brook 1,4-rearrangement and tosylate substitution. The method is particularly suitable for the preparation of cyclopentanes, whereas cyclohexanes and -heptanes are formed in yields only up to 49%. Use of enantiomerically pure epoxides provides optically active cyclopentanes (S)-10b, d, 11a as well as oxetanes (S)-14a, b. Hydrolysis of the dithioacetal function leads to the corresponding ketones 12, Cyclization of epoxide 24b gives an anellated cyclopentane 26, the configuration of which was established by X-ray structural analysis of dinitrobenzoate 27. Use of epoxide 29b provides the anellated tetrahydrofuran 30.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1481-1488 
    ISSN: 1434-193X
    Keywords: Thiolane 1-oxides ; Carbanions ; Oxiranes ; Asymmetric synthesis ; X-ray structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Carbanions of the 2-(alkylthio)thiolane 1-oxides 1 and 2 are generated and subjected to reaction with the epoxides 3-5. The resulting carbinols 6-11 are formed with high α diastereoselectivity, which is explained by a stabilization of the trans configuration of the carbanions in the activated complex. A minor γ stereoselectivity is also observed in case of the reactions with 4 and 5. The pure enantiomers (1S,2S,2′S)-9a and (1R,2R,2′S)-11b were obtained from 2 and (S)-4 or (R)-5, respectively, and their configurations were proved by X-ray structural analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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