1,3-Rearrangements of some allylic sulphones
- 1 January 1987
- journal article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- p. 2707-2713
- https://doi.org/10.1039/p19870002707
Abstract
The 1,3-rearrangement of a number of acyclic and cyclic allylic p-tolyl sulphones has been found to occur on treatment (a) with benzoyl peroxide (BPO) in CCl4 under reflux or (b) with sodium toluene-p-sulphinate in aqueous acetic acid at 110 °C. Rearrangement is only successful in cases where the product sulphone is thermodynamically more stable than the starting material, e.g. prenyl† sulphone (10) is obtained from dimethylallyl sulphone (9). A radical chain addition–elimination mechanism involving arenesulphonyl radicals is proposed. More heavily substituted cyclic allylic sulphones such as 1-methylcyclohex-2-enyl p-tolyl sulphone (21; R = Me) rearranged only sluggishly under the BPO–CCl4 conditions but underwent smooth isomerisation to (22; R = Me) on being heated in AcOH–water (3 : 2) at 110 °C. Evidence is presented in favour of an ion-pair dissociation-recombination mechanism in these cases.Keywords
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