A ‘green’ and high-yielding electrochemical method for performing tin-free, intermolecular radical reactions (the Giese reaction) has been developed.

The hazards and difficulties of handling elemental halogens such as I2 can be circumvented through the electrochemical generation of these species in situ and ‘on‐demand’. Advantages of this approach include the halogen being introduced into the reaction mixture at a steady rate, ensuring low concentrations to prevent halogenation of reactive aromatic rings. We also demonstrate that the Lewis acid required to promote this reaction, a Zn(II) salt, can also be generated in situ from a zinc‐coated graphite electrode in a clean and energy‐efficient manner. Mechanistic studies indicate an unusual pathway, which provides selectivity for the iodocyclisation without the often‐problematic electrophilic aromatic iodination of the aryl ring.

Mechanistic studies of a reactive oxygen species mediated electrochemical radical reaction of alkyl iodides are described. Hydroxyl radicals and ozone are identified to be the active species invoved in the...