Electrochemical investigation on prostaglandin F2α derivatives. I. Anodic iodination of prostaglandin F2α and its methylesther

Studies of the anodic iodination of prostaglandin F2α were carried out under a variety of electrolytic conditions. The effect of anode material, potential, pH of the electrolyte, initial substrate concentration and charge passed were investigated. A preparative technique for the iodination, in an undivided cell, has been developed. The iodinated compound-in the form of its 6-endo-(H)isomer-can be obtained in a two-electron process, with 100% conversion and nearly a quantitative product and current yield, without by-products, when using a platinum anode and cathode, +1.5 V vs SCE potential and 30 vol% methanolic 1 M aqueous citrate buffer solution (pH 3.4–3.6) containing 1–2×10−2 M of the substrate and KI as electrolyte. The method can be extended to other prostaglandin derivatives. On the basis of the experimental results a mechanism is proposed involving the iodine radical and the iodinated substrate radical as intermediates.