THE MECHANISM OF ELECTROCLEAVAGE REACTIONS AND PHOTOREARRANGEMENTS OF SOME SULFONIUM SALT DERIVATIVES

Article abstract of DOI:10.1016/S0040-4020(01)88072-8

Irreversible one-electron reduction potentials (E_p) measured for a series of arylmethyl substituted-alkyl sulfonium salts (aryl=phenyl and 1-naphthyl) indicate that reductive cleavage occurs by a concerted mechanism in which bond breaking is concomitant with electron acceptance.Photolysis of the 1-naphtylmethyl substituted-alkyl sulfonium salts produces 1-thiomethy-2-substituted-alkyl naphthylenes via a 1,3-sigmatropic rearrangement along with cleavage products.An in-cage fragmentation-recombination process involving cation-radical/radical intermediates is favored as the rearrangement mechanism even though a concerted pathway may be involved to some extent. p-Cyanobenzylthianthrene sulfonium trifluoromethanesulfonate also underwent photochemically as well as thermally induced rearrangement of the p-cyanobenzyl group from sulfur to the 1- and 2-position of the thianthrene ring system.An in-cage fragmentation-recombination mechanism is also favored in this case for both photochemical and thermal processes.