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  • 2H-1,2-Thiazete 1,1-dioxides  (1)
  • Asymmetric synthesis  (1)
  • Cyclization, stereocontrolled  (1)
  • Diaminothioketene S,S-dioxide  (1)
  • 1
    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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  • 2
    ISSN: 0947-3440
    Keywords: [2 + 2] Cycloadditions ; 2H-1,2-Thiazete 1,1-dioxides ; Amidinosulfenes, in situ formation of ; Diaminothioketene S,S-dioxide ; 1,3-Dithietane 1,1,3,3-tetraoxide ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Sulfonylalkylamines 2a, b react with ynamines 3 to give primarily 2H-1,2-thiazete 1,1-dioxides 4. But, except for the 4-triphenylsilyl species 4a, b, these products are unstable and undergo electrocyclic ring opening to very reactive amidinosulfenes 5, which are transformed into different products, depending on the ynamine substituents R2. The 1,3-dithietane 1,1,3,3-tetraoxide 8 is formed from N-sulfonylisopropylamine (2a) and the trimethylsilyl-substituted ynamine 3b via amidinosulfene 5c and probably thioketene S,S-dioxide 7. On the other hand, (isopropylamidino)sulfene 5d dimerizes to the 2H-1,5,2-dithiazine 9 and also gives the [2 + 4] cycloadducts 10a, 11a by reaction with 2a and ynamine 3c, respectively. In contrast, it was possible to trap phenyl-substituted amidinosulfenes 5e-h by addition of water or methanol.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0947-3440
    Keywords: Tetrahydrofurans, formation of ; Cyclization, stereocontrolled ; Vinylsilanes ; Allylsilanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silyl-substituted 4-alken-1-ols cyclize in the presence of a wide range of electrophilic reagents to give substituted tetra-hydrofurans. The silyl group accelerates ring closure by its β-effect and its position determines the efficiency of stereo-control. Thus, a vinylic silyl group as in 1, 3-9 gives mixtures of 2,5-disubstituted tetrahydrofurans 2, 10-21, favoring formation of the trans isomer. In contrast, an allylic silyl group as in 28-30 exerts a high degree of stereocontrol, generally affording 2,3-trans-disubstituted tetrahydrofurans 31-36.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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