The Iodination of Strongly Electron-Deficient Arenes under Electrochemical Conditions with I2 and Catalytic Amounts of Chloride Anions

The electrochemical iodination of electron-deficient arenes beyond the hitherto described scope of such reactions performed with other iodinating agents is realized in a divided cell at a platinum anode in nitromethane utilizing I2 in stoichiometric amounts and catalytic amounts of Bu4NCl. The electrolysis generates the proposed reactive species [I2Cl]+ · CH3NO2 in the anode compartment (4.2 mA·cm−2) on a 0.25–1.00 mmol scale and leads to the desired meta-substituted iodinated products in high to excellent regioselectivities. For the iodination of dimethyl phthalate as electron-deficient arenes, which gave a mixture of products, the reactivity and the regioselectivity of the I2/Cl− system can be fine-tuned to a certain degree by addition of small amounts of Bu4NI, so that a unique variable electrochemical iodinating system could be established.