1,3-Rearrangement of allylic sulphones: Rearrangement-cyclisation of allylic 4-pentenyl sulphones

Article abstract of DOI:10.1016/S0040-4039(00)60462-8

Allylic alkyl sulphones CH₂:CHC(Me)₂SO₂R (R=Me, Et, iPr, tBu, CH₂SiMe₃, CH₂CH₂SiMe₃, and CH₂CH(OH)Me underwent 1,3-rearrangement on treatment with benzoyl peroxide in tBuOH. 1,3-Rearrangement did not occur in cases (R=CH₂Ph, CH₂COMe) where the intermediate sulphonyl radical RSO₂· could undergo loss of sulphur dioxide to form a resonance-stabilised alkyl radical. Allylic 4-pentenyl sulphones undergo rearrangement with accompanying cyclisation of the intermediate radical, this process is more efficient if the allylic sulphone bears an electron withdrawing group at the β-position.