The thermal transformations of bicyclopropylidene and methylenespiropentane revisited

Schill, H., Kozhushkov, S.I., Walsh, R. and de Meijere, A. (2007) The thermal transformations of bicyclopropylidene and methylenespiropentane revisited. European Journal of Organic Chemistry (9). pp. 1510-1516. ISSN 1434-193X doi: 10.1002/ejoc.200601100

Abstract/Summary

The overall and the individual rate constants of the unimolecular thermal isomerization of methylenespiropentane (4) to 1,2- and 1,3-dimethylenecyclobutanes (7 and 8) have been determined to be lg (k(-4)/s(-1)) = (13.78 +/- 0.06) - (49.7 +/- 0.2) kcal mol(-1)/RT.ln 10, lg(k(7)/s(-1)) = (13.03 +/- 0.19) - (48.0 +/- 0.6) kcal mol(-1)/RT.ln 10 and lg(k(8)/s(-1)) = (14.15 +/- 0.19) - (52.4 +/- 0.5) kcal mol(-1)/RT.ln 10, respectively. The activation energies are significantly lower than that for the rearrangement of the parent spiropentane. ((c) Wiley-VCH Verlag GmbH & Co.