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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: Formation of Chiral, Alicyclic Ethers by Addition of Carbohydrates to Cyclohexene in Hydrogen FluorideD-Ribose (1a) reacts with cyclohexene in liquid hydrogen fluoride to give (2R,3R3aR,4aR, 8 aS, 8bR)-perhydro-2-(hydroxymethyl)furo[3,2-b]benzofuran-3-ol (2a) and (3R,4R,4aR,5 aR,9 aS,9 bR)-perhydro-pyrano[3,2-b]benzofuran-3,4-diol (3a). Use of 5-O-methyl-D-ribofuranose (1b) leads exclusively to the formation of 2c, the 9-O-methyl derivative of 2a. Reaction of D-mannose (4), L-rhamnose (7), and D-erythro-pentulofuranose (9) yields the substitutionally isomeric, tricyclic ethers 5a, 6a, 8a, and 10; besides 10, sample 9 also yields the two tricyclic spiro ethers 11a and 11b.  -  The structure of 2a has been confirmed by an X-ray analysis.
    Notes: D-Ribose (1a) reagiert mit Cyclohexen in flüssigem Fluorwasserstoff zu (2R,3R3aR,4aR, 8 aS, 8bR)-Perhydro-2-(hydroxymethyl)furo[3,2-b]benzofuran-3-ol (2a) und (3R,4R,4aR,5 aR,9 aS,9 bR)-Perhydro-pyrano[3,2-b]benzofuran-3,4-diol (3a). Der Einsatz von 5-O-Methyl-D-ribofuranose (1b) führt zur ausschließlichen Bildung von 2c, dem 9-O-Methyl-Derivat von 2a. Die Umsetzung von D-Mannose (4), L-Rhamnose (7) sowie D-erythro-Pentulofuranose (9) führt zu den substitutionsisomeren tricyclischen Ethern 5a, 6a, 8a und 10; 9 liefert neben 10 auch die beiden tricyclischen Spiro-Ether 11a und 11b.  -  Die Struktur von 2a wurde durch eine röntgenographische Untersuchung bestätigt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1986 (1986), S. 787-798 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Carbohydrates with Tetracyanoethylene in Anhydrous Hydrogen FluorideThe pentoses D-ribose (1), D-xylose (3), and D-lyxose (8) react with tetracyanoethylene and ethanol in liquid hydrogen fluoride to give the correspondingly configurated 2-[perhydro-6-hydroxy-5-(hydroxymethyl)furo[2,3-d]oxazol-2-ylidene]cyanoacetic acid esters (2, 4, and 10) in high yields. D-Arabinose (9) also gives, besides the furanoid main product 11, the isomer 12 with pyranoid carbohydrate moiety. The reaction of D-glucose (13), however, leads to the pyranoid product 14 besides small amounts of the furanoid bicyclus 15. The synthesis is transferable also to other aldohexoses. D-Fructose (16) yields, besides 18, the spiro derivatives 17 and 19. - The structure of 4 was confirmed by X-ray analysis.
    Notes: Die Pentosen D-Ribose (1), D-Xylose (3) und D-Lyxose (8) reagieren mit Tetracyanethylen (TCNE) und Ethanol in flüssigem Fluorwasserstoff in hohen Ausbeuten zu den entsprechend konfigurierten 2-[Perhydro-6-hydroxy-5-(hydroxymethyl)furo[2,3-d]oxazol-2-yliden]cyanessigsäureestern (2, 4 und 10). D-Arabinose (9) liefert neben dem furanoiden Hauptprodukt 11 auch das Isomer 12 mit pyranoidem Kohlenhydratanteil. D-Glucose (13) reagiert dagegen hauptsächlich zum pyranoiden Produkt 14 und in geringen Anteilen zum furanoiden Bicyclus 15. Die Synthese läßt sich auch auf andere Aldohexosen übertragen. D-Fructose (16) ergibt neben 18, die beiden Spiroverbindungen 17 und 19. - Die Struktur von 4 wurde durch eine Röntgenstrukturanalyse abgesichert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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