The importance of polar, resonance, steric and solvent effects in the addition of sulfonyl radicals to alkenes

Abstract

The radical chain addition of tosyl iodide to some alkenes has been studied. The reaction was carried out at room temperature under visible light, giving the usual high yields of β-iodo sulfones. These adducts were transformed into the corresponding unsaturated sulfones. Relative reactivities of the addition of the tosyl radical to alkenes were measured in acetonitrile, dichloromethane and carbon tetrachloride, the effect of the solvent being important only with polarized alkenes, such as vinyl and allyl cyanides, which are stabilized in solvents with greater π* and AN parameters. The delocalization of the unpaired electron in the adduct radicals over the carbonyl and cyano groups is not important; the phenyl group is the only group that is able to affect the reactivity, increasing it notably. Polar and steric effects are dominant in all the other cases.