Oxidative Cleavage and Cyclization of Disulfide Carboxylic Acids and Alcohols by Aqueous Iodine: A Facile Route to Five-Membered Ring Sultines

Article abstract of DOI:10.1021/jo00350a054

The kinetics and mechanism of the oxidative cleavage by aqueous iodine of disulfide carboxylic acids and alcohols are presented.There is evidence for intramolecular interaction of the oxygen nucleophiles.The sole product of the iodine oxidation of 3,3'-dithiodipropanol is the sultine 1,2-oxathiolane 2-oxide, which is formed after the rate-determining step, apparently via rapid cyclization of the sulfenyl iodide.The anchimeric assistance provided by the neighboring carboxylate group in the reaction of 3,3'-dithiodipropanoic acid is responsible for the pH profile of the rate of oxidative cleavage.At a given pH, the rate law for the reaction is -d/dt = k_I3^->(0.0905->^-1 + 0.0019->^-2).The inverse second term in iodide ion not has been observed previously in kinetic studies of disulfide reactions and is interpreted as evidence for a disulfide-iodonium complex.