The use of sulfur dioxide as an electron transfer mediator in the presence of nitrogen bases permits the rather selective fluoroalkylation of thiophenols, phenols, and pyrrole by Freons BrCF 2 CF 2 Br and CF 2 ClCFCl 2 under mild conditions. In the case of thiophenols, the fluoroalkylation occurs to give polyfluoroalkyl aryl sulfides, while phenols and pyrrole are alkylated in the ring. Effects were found for the electronic structure of the substrates and basicity of the medium (pK a of the pyridines) on the oxidation-reduction properties of the reagents and the efficiency of the reactions studied.The activation of Freons and the search for nontraditional methods for the use of these compounds are the subject of current research. A promising approach involves the use of Freons as sources of fluoroalkyl groups in the synthesis of various fluorine compounds [1][2][3][4][5]. Especial interest is found in Freons containing several other halogen atoms in addition to fluorine such as Freons F114B2 (BrCF 2 CF 2 Br), F113 (CF 2 ClCFCl 2 ), and F113B2 (BrCF 2 CFClBr), which permits not only the synthesis of a series of new derivatives but also may significantly expand the synthetic possibilities in the subsequent transformation of simple fluorine-containing substituents into complex groups as demonstrated by various workers [6][7][8]. Equally significant is that Freons as fluoroalkylating agents are much less expensive than iodoperfluoroalkanes.As inert compounds, Freons do not react under ordinary conditions even with such extremely reactive organic substrates as thiophenols, phenols, and heterocyclic nitrogen derivatives as well as many other organic compounds. Potassium salts of these substrates are usually used for fluoroalkylation [9][10][11][12], as found, in particular, in the reaction of thiophenols and phenols with halogen-containing fluoroalkanes:(1) 2ArZK + 2Hal 1 (CF 2 ) n CF 2 Hal 2 ® ArZ(CF 2 ) n CF 2 Hal 2 + ArZ(CF 2 ) n CF 2 H + 2KHal 1 (Z = S, O).However, a large amount of a side-product, ArZ(CF 2 ) n CF 2 H is formed in the condensation with replacement of a halogen atom by hydrogen along with the halogen-containing product ArZ(CF 2 ) n CF 2 Hal 2 (scheme (1)). The fraction of the hydrogen-substituted product becomes predominant and the total overall product yield of fluoroalkylation products drops with increasing electron-withdrawing properties of the substituents in the aromatic thiophenolate ring.In the present work, we attempted to elucidate the feasibility of fluoroalkylation of thiophenols, phenols, and pyrrole as starting reagents, using Freons BrCF 2 CF 2 Br and CF 2 ClCFCl 2 , avoiding formation of salts of these substrates, which would 0040-5760/07/4305-0343