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Cyclisation of alfa-cyano-alfa-sulfonyl-gamma,delta-epoxy carbanions proceeds with high yields and complete diastereoselectivity to yield cyclopropanolactones, useful intermediates in the synthesis of cis-substituted cyclopropane carboxylic acids.

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.

We report a systematic study on the 13C nmr chemical shifts of geminal bis-sulfones; stereochemical implications, in particular on the conformation of the title compounds, are also discussed.

Reactions of 1-aminocyclopentenes with acyl aryldiazenes give 1:1 enaminic adducts or 1,3,4-oxadiazines. Isolation of these products was not always possible in the reactions of 1-(piperidin-1-yl)- and 1-(pyrrolidin-1-yl)-cyclopentene. Acidic hydrolysis gave 2-(N-acyl-N'-aryl)hydrazinocyclopentanones or 2-arylaminocyclopentenones, depending upon the amine moiety and the cyclic or open chain nature of the adducts.

The reactions of the title compound with secondary amines, alcohols, and enamines have been studied. Addition or addition-elimination at either electrophilic position is observed. Regiochemistry is a function of steric and electronic effects and of electrostatic interactions

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.

Formation of β- and α-adducts in the reactions of styryl sulphones with enamines from 4-alkylcyclohexanones is reexamined. Steric effects, electrostatic interactions between the nitrogen atom of the enamine and the oxygen atoms of the sulphone group, and medium effects contribute to the regioselectivity of the reaction.