Electrogeneration of Triphenyltin Radical, Anion and Cation. Electrochemical Initiation of Tin Hydride-Promoted Radical Chain Reactions.

Tanaka, H.; Ogawa, H.; Suga, H.; Torii, S.; Jutand, A.*; Aziz, S.*; Suarez , A. G.*; Amatore, C. * (*Ecole Normale Superieure), J. Org. Chem. 1996, 61, 9402.

In our research of precursors of tin radicals able to initiate radical chain reactions under mild conditions, a series of triphenyltin derivatives Ph₃SnY (Y = H, I, Cl, OTf, OCHO, SnPh₃, SPh ) is investigated by cyclic voltammetry. The results show that the tin radical Ph₃Sn･ is only produced from two compounds: by a one electron oxidation of Ph₃SnH or by a one electron reduction of Ph₃SnI. Therefore electrooxidation of Ph₃SnH generates Ph₃Sn･ which is able to initiate cyclization of haloalkynes. Reduction or oxidation of the other derivatives affords respectively the anion Ph₃Sn^- or the cation Ph₃Sn⁺ because they are generated at potentials where the radical Ph₃Sn･ is either reduced or oxidized.