911225-20-2Relevant academic research and scientific papers
Extremely facile ring inversion and rearrangement in fluorobicyclo[2.1.0]pentanes
Wei, Yanjun,Liu, Yufa,Wong, Terrence,Lemal, David M.
, p. 688 - 703 (2008/09/16)
cis-1,2,3,4,5,5-Hexafluorobicyclo[2.1.0]pentane and 1,2,4,5-tetrafluorobicyclo[2.1.0]pentane have been synthesized from hexafluorobenzene. The former hydrofluorocarbon, which exists entirely in the endo configuration, rearranges to cis-1,2,3,3,4,5-hexafluorocyclopentene below room temperature (Ea = 21.9 kcal/mol, log A = 13.4). The latter undergoes degenerate ring inversion with extraordinary ease (ΔG? = 6.8 ± 0.2 kcal/mol at -55 °C). Density functional calculations indicate that significant bonding between the bridgehead carbons is retained in the ring inversion transition state. Analogous calculations predict for hexafluorobicyclo[1.1.0]butane a considerably lower barrier for ring inversion and more 1,3-bonding in the transition state.
