Stereochemistry of the C−S Bond Cleavage in cis-2-Methylcyclopentyl Phenyl Sulfoxide Radical Cation

The TiO(2) photocatalyzed oxidation of cis-2-methylcyclopentyl phenyl sulfoxide in the presence of Ag(2)SO(4) in MeCN/H(2)O leads to the formation of 1-methylcyclopentanol, 1-methylcyclopentyl acetamide, and phenyl benzenethiosulfonate as the main reaction products. It is suggested that the C-S heterolysis in the radical cation is an unimolecular process leading to an ion radical pair. Fast 1,2-hydride shift in the secondary carbocation leads to 1-methylcyclopentyl carbocation that forms the observed products by reaction with H(2)O and MeCN. Attack of H(2)O on the ion radical pair may also occur, but as a minor route (<3%), with formation of trans-2-methylcyclopentanol.