Theoretical study of the walk rearrangement in perfluorotetramethyl (Dewar thiophene) exo-S-oxide

A theoretical study of the 'walk' rearrangement in bicyclo[2.1.0]pentene and perfluorotetramethyl (Dewar thiophene) exo-S-oxide has been carried out. Despite the differences between them, the results for both reactions show an enhancement of aromaticity in the transition state, which is consistent with a pericyclic behavior. NBO calculations show that the small activation energy for the second reaction can be interpreted in terms of a strong stabilization of the transition state by the exo-oxide substituent. So, the mechanism proposed in the past should be revised.

The mechanism of this walk rearrangement was theoretically studied. The definition of pseudopericyclic reaction was based on the experimental behavior of this compound, which undergoes an extraordinarily facile automerization.