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  • Conformational analysis  (1)
  • Cyanoacetylenes  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Improved Synthesis, Structure, and Cycloaddition Reaction of [34](1,2,4,5)Cyclophane (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1223-1231 
    Details
    ISSN: 1434-193X
    Keywords: Cyclophanes ; Barrelenophanes ; Semibullvalenophanes ; Cycloadditions ; Cyanoacetylenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The modified synthetic route to [34](1,2,4,5)cyclophane (3) provides gram quantities of this compound in fewer steps than the conventional routes. The cycloaddition of 3 with dicyanoacetylene (12) gave barrelenophane 13, which was transformed into semibullvalenophane 15 on photoirradiation. This transformation (13 → 15) is in sharp contrast to the case of Boekelheide's [24]barrelenophane, where cyclooctatetraenophane is obtained. The X-ray structural analyses of 3, 13, and 15 demonstrates their unique structures.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    A Conformational Study of [3.3](2,6)Pyridinophane by the Dynamic NMR Method and X-ray Structural Analysis (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1645-1649 
    Details
    ISSN: 0947-3440
    Keywords: [3.3](2,6)Pyridinophanes ; Conformational analysis ; Hydrogen bond ; Dynamic NMR spectroscopy ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variable-temperature 1H-NMR study and X-ray structural analysis show that the most stable conformational isomer of [3.3](2,6)pyridinophane 2 is the syn(boat-boat) conformer, and the relative stability order of the three stable conformers is syn(boat-boat) 〉 syn(chair-boat) 〉 syn(chair-chair). This is in sharp contrast to the relative stability order of the parent [3.3]metacyclophane 1: syn(chair-chair) 〉 syn(chair-boat) 〉 syn(boat-boat). The high stability of the syn(boat-boat) conformer 2c is primarily attributed to weak attractive interactions via intramolecular hydrogen bonds between nitrogen lone pairs (N-1, N-2) and the axial hydrogen atoms (2A-H, 11A-H) on the central carbon atoms of the bridges, as suggested by their short transannular distances (2.50 Å).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961023
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    Paper (German National Licenses)
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