Abstract
From racemization studies on optically active [2.2]metacyclophanes substituted in position 4, the parameters of activation for the inversion of the tenmembered ring were found to be: ΔG ≠423 =31.5 kcal/mole, ΔH ≠=27.5 kcal/mole and ΔS ≠=−10 Cl/mole.
Racemization does not occurvia bond forming or breaking; the value for the inversion barrier is not affected by substituents in position 4 and therefore corresponds to the value of unsubstituted [2.2]metacyclophane, whereas substituents in the bridge exert a distinct influence. These results can easily be explained on the basis of the “isoconformational” concept.
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Glotzmann, C., Langer, E., Lehner, H. et al. Die Ringinversions-Barriere in [2.2]Metacyclophan. Monatshefte für Chemie 105, 907–916 (1974). https://doi.org/10.1007/BF00910256
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DOI: https://doi.org/10.1007/BF00910256