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A new general process of selective, homolyticalkylation of heteroaromatic bases of great synthetic interest is described. It is based on the reaction of alkyl iodides with hydrogen peroxide and heterocyclic compounds in DMSO, catalyzed by an Fe (II) salt. It is shown that the iodine abstraction from the alkyl iodide by the methyl radical, generated from the solvent, is the key point of the overall process. Combined enthalpic and polar effects contribute to the high selectivity: the enthalpic factorgoverns the equilibria of the iodine abstraction, and the polar factor determines the reactivity toward the protonated heterocyclic ring.

In 1968 we showed, in a preliminary report, 1 that a va-riety of selective reactions could be realized by taking advantage of the polar effects arising from the nucleophilic character of carbon-centered radicals in reactions with electron-deficient substrates (olefins conjugated with electron-withdrawing …