TUD Organische ChemieImmelPublicationsPapersAbstract 34View or Print (this frame only)View or Print (this frame only)

Molecular Modeling of Saccharides, Part XXIX.

Hydroxymethyl-substituted crown acetals with 35-C-14 and 40-C-16 skeletal backbones: Synthesis and molecular geometries

S. Immel, F. W. Lichtenthaler, H. J. Lindner, and T. Nakagawa

Tetrahedron: Asymmetry 2001, 12, 2767-2774.

An oxidation/reduction sequence readily converts β- and γ-cyclodextrin into hydroxymethyl-substituted crown acetals with 35-C-14 and 40-C-16 skeletal cores. X-Ray analysis of their well crystallizing peracetates reveals the 40-membered ring of the γ-CD derived octaacetal to mould into an undulated four-loop structure with alternating gauche and anti-conformations of the eight meso-butanetetrol units, the overall shape resembling a four-leaf clover. In the β-CD derived, 35-membered crown heptaacetal, six of the seven glycolaldehyde/butanetetrol segments are lined up in alternating gauche/anti arrangements with the seventh, uneven unit inserted in gauche orientation. In solution, however, the macrocycles are highly flexible as evidenced by their 1H and 13C NMR spectra, which at 300 K show only one set of signals for the respective -CHR-CHR-O-CHR-O- units (R = CH2OH or CH2OAc).

Additional Graphics: Crown Acetals

Citations:

  1. Immel, S.; Khanbabaee, L., Tetrahedron: Asymmetry 2000 pp. 2495-2507
  2. Pedersen, C.J., J. Am. Chem. Soc. 1970 pp. 391-394
  3. Known tetraoxacycloalkanes with two acetal units in their n-crown-4 skeletal backbone: (a) 10-C-4: Bassi, I. W.; Scordamaglia, T.; Fiori, L. J. Chem. Soc., Perkin Trans. 2 1975, 1129–1132; (b) Substituted 10-C4-systems: Terzis, A.; Grindley, T. B. Can. J. Chem. 1979, 57, 2154–2158; Stoddart, J. F.; Szarek, W. A. Can. J. Chem. 1968, 46, 3061–3069; (c) 12-C-4; Borgen, G.; Dale, J. J. Chem. Soc., Chem. Commun. 1974, 484–485; Dale, J. Tetrahedron 1974, 30, 1683–1694; (d) 14-C-4: Bassi, I. W.; Scordamaglia, R.; Fiori, L. J. Chem. Soc. Perkin Trans. 2 1972, 1726–1729; (e) 16-C-4: Dale, J.; Ekeland, T. Acta Chem. Scand., Ser. A 1973, 27, 1519–1525; Groth, P. Acta Chem. Scand., Ser. A 1975, 29, 642–643; (f) 18-C-4, 24-C-4, 26-C-4, and 34-C-4: Hill, J. W.; Carothers, W. H. J. Am. Chem. Soc. 1935, 57, 925–928.
  4. The cyclo-polyacetals generated by acid promoted oligomerization of 1,3-dioxolane are presumed to have 15-C-6, 20-C-8, and 25-C-10 structural backbones (Kawakami, Y.; Yamashita, Y. Macromolecules 1977, 10, 837–839), yet their ring size has not been established unambiguously.
  5. French, D.; McIntyre, R.J., J. Am. Chem. Soc. 1950 pp. 5148-5150
  6. Stoddart, J.F.; Szarek, W.A.; Jones, J.K.N., Can. J. Chem. 1969 pp. 3213-3215
  7. Immel, S.; Nakagawa, T.; Lindner, H.-J.; Lichtenthaler, F.W., Chem. Eur. J. 2000 pp. 3366-3371
  8. Koshland, D. E. Angew. Chem. 1994, 106, 2468–2472; Angew. Chem., Int. Ed. Engl. 1994, 33, 2375–2378.
  9. Fischer, E., Ber. Dtsch. Chem. Ges. 1884 pp. 2985-2993
  10. Fujita, K.; Chen, W.-H.; Yuan, D.-Y.; Nogami, Y.; Koga, T.; Fujioka, T.; Mihashi, K.; Immel, S.; Lichtenthaler, F.W., Tetrahedron: Asymmetry 1999 pp. 1689-1696
  11. McKinnon, J.J.; Mitchell, A.S.; Spackman, M.A., Chem. Eur. J. 1998 pp. 2136-2141
  12. Connolly, M.L., J. Appl. Crystallogr. 1983 pp. 548-558
  13. Sheldrick, G. M. SHELXS-97 and SHELXL-97—Programs for Crystal Structure Solution and Refinement; University of Göttingen: Germany, 1997.
  14. Immel, S. MolArch+—MOLecular ARCHitecture Modeling Program; Darmstadt University of Technology: Germany, 2001.

© Copyright PD Dr. S. Immel