Nonclassical 21-Homododecahedryl Cation Rearrangement Revisited

The degenerate rearrangement in the 21-homododecahedryl cation (1) has been studied via density functional theory computations and Born–Oppenheimer Molecular Dynamics simulations. Compound 1 can be described as a highly fluxional hyperconjugated carbocation. Complete scrambling of 1 can be achieved by the combination of two unveiled barrierless processes. The first one is a “rotation” of one of the six-membered rings via a 0.8 kcal·mol–1 barrier, and the second one is a slower interconvertion between two hyperconjomers via an out-of-plane methine bending (ΔG ⧧ = 4.0 kcal·mol–1).