The 9-homocubyl cation rearrangement revisited

Abstract

Complexity of the potential energy surface of the 9-homocubyl cation is revealed by Born-Oppenheimer molecular dynamics simulations and high ab initio levels. The stereospecific automerizations observed experimentally involve bridged ions, which have either an aromatic or an anti-aromatic character. New pathways leading to more stable isomers are unveiled.

Dynamic behavior of rearranging carbocations – implications for terpene biosynthesis

“…The shorter mechanism was found to involve nine discrete chemical steps and had an overall predicted activation barrier of 33 kcal/mol, while the longer pathway involved 16 steps with an overall barrier of 37 kcal/mol. Similar results have been obtained for other complex carbocations: the same group used molecular dynamics to explore the homocubyl cation’s rearrangement behavior [ 68 ], and East et al used “rising-temperature” molecular dynamics to determine the carbocation branching behavior of molecules relevant to petroleum chemistry [ 69 – 71 ].…”

Revisiting the Rearrangement of Dewar Thiophenes

“…To overcome this mechanistic conundrum, Lemal et al proposed the participation of a nonbonding sulphur lone pair, implying an alternative nonpericyclic mechanism" [6]. Some of us have been interested in rearrangements in organic systems [7][8][9][10][11] for a long time and this system represents an exciting case to apply different tools to explain its dynamical behavior. The mechanism for Dewar rearrangements has been a subject of study since its discovery [2][3][4][5][6].…”

Shape-selective crystallisation of fluxional carbon cages

“…Fluxional carbon cages, such as bullvalene1 and the barbaralyl cation2 (Fig. 1a), undergo reversible pericyclic rearrangements on a grand scale 3. Sequential, low-energy steps interconvert large numbers of degenerate isomers.…”