Circumambulatory rearrangements of cyclopolyenes containing element-centred migrants

Data on circumambulatory rearrangements caused by rapid migrations of substituents formed by Group 13–17 elements around three- to nine-membered cyclopolyenes are generalised and systematised. Depending on the ring size, the nature of the migrating group, substituents in the ring and the medium, the rate constants of circumambulatory rearrangements vary over a wide range from 106 to 10−8 s−1 at room temperature. Particular attention is given to analysis of the mechanisms of these rearrangements ([1, j]-, [2,3]- and [3,3]-sigmatropic shifts, haptotropic rearrangements and ionisation–recombination) and to the correlation of these mechanisms with the structural characteristics of the compounds that undergo rearrangements.