|TUD Organische Chemie||Immel||Publications||Poster||Abstract 10||View or Print (this frame only)|
Holger Gohlke, Stefan Immel, Frieder W. Lichtenthaler, and Guido Schmitt
9thInternational Symposium on Cyclodextrins, Santiago de Compostela, Spain, May 31-June 3, 1998, Abstract 2-P-4.
Various cyclooligosaccharides composed of β(1→3)-, β(1→5)-, and β(1→6)-linked galactofuranose units have been prepared by cycloglycosylation of tritylated 1,2-O-(1-cyano)ethylidene-derivatives of D-galactofuranose, yet information as to their molecular geometries and particularly to their inclusion complex behavior is essentially non-existent. To get a first assessment of the conformational features involved we have subjected the cyclogalactins 1 - 4 to PIMM91 Monte Carlo simulations:
The results reveal a comparatively high flexibility of the cyclic furanosides, rendering the molecules with irregular, asymmetric overall shapes rather than symmetrical geometries. In contrast to cyclogalactins composed of pyranoid units, calculation of the corresponding molecular surfaces and the cross section cuts of 1 - 4 displays them to be disk-shaped and devoid of central cavities.
N. K. Kochetkov, S. A. Nepogodiev, L. V. Backinowsky, Carbohydr. Res. 1989, 185, C1-C3; Tetrahedron 1990, 46, 139-150.
F. W. Lichtenthaler, S. Immel, Tetrahedron: Asymmetry 1994, 5, 2045-2060.
Additional Graphics: Cyclogalactins