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Styryl sulphones undergo nucleophilic addition, with the nucleophile adding at the α- or the β-position, with respect to the sulphone group; β-attack is normally favoured over α-attack. Factors which can change the regioselectivity in favour of the addition of the nucleophile to the α-position are discussed for heteronucleophiles as well as carbon nucleophiles.

A quantitative study on the effects of methyl and gem-dimethyl groups in the intramolecular ring opening of epoxides by bis-sulfonyl carbanions is reported for the formation of cyclopropanes. Reaction rates are increased by methyl groups on the chain connecting the nucleophile with the oxirane and depressed by methyl substitution in the epoxide ring. When gem-dimethyl groups are present on the epoxide, ring opening is apparently inhibited. It will be shown that in this case the reaction is reversible and the apparent stabilization of the gem-dimethyl- substituted oxirane is actually due to a combination of effects on both the forward and the reverse reactions. On the basis of current theories on intramolecular reactions, it is suggested that release of ground-state strain and van der Waals repulsions in the transition state can account for the observed reactivity.