摘要：

Bullvalene is a fascinating compound that undergoes a rapid, degenerate rearrangement, interchanging all atoms with an activation energy of 11.8 ± 1 kcal/mol. After the first synthesis by Schroder, rearrangement was demonstrated by NMR and by preparing substituted bullvalenes. For example, halogenation of bullvalene produces a thermodynamic mixture of isomers. The carbocation formed from the ionization of halobullvalenes would be of great interest. If the positive charge were on the carbon along the threefold axis, it would be a bridgehead cation, which would formally be triply allylic and in homoconjugation with three cyclopropylcarbinyl centers. However, this conjugation would be inhibited by the lack of overlap between the p orbital and the π orbitals of the double bonds.

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