From 13C NMR coalescence temperature measurements, free energies of activation for degenerate ring reversal in two configurationally isomeric dicyclohexano-18-crown-6 ethers have been determined to be ca. 10.2 kcal/mole, with higher barriers for the 1:1 complexes with potassium phenoxide.

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Persistent URL dx.doi.org/10.1016/0040-4039(84)80041-6
Journal Tetrahedron Letters
Citation
Buchanan, G.W, Bourque, K., Bovenkamp, J.W., Rodrigue, A., & Bannard, R.A.B. (1984). Stereochemical dynamics of crown ethers: Ring inversion in isomeric dicyclohexano-18-crown-6 systems as studied by 13C magnetic resonance at low temperature. Tetrahedron Letters, 25(36), 3963–3966. doi:10.1016/0040-4039(84)80041-6