A new strategy for catalytic functionalization of C-H bonds by means of electrochemical oxidation is described. Combination of palladium-catalyzed aromatic C-H bond cleavage and halogenation with electrochemically generated halonium ions enables highly efficient, selective halogenations of aromatic compounds in a green-sustainable manner. The required reagents for this reaction are an arene and an aqueous hydrogen halide as substrates, a palladium salt as a catalyst, and an organic solvent. No further additives such as electrolytes, oxidants, or ligands are necessary to achieve effective catalytic activity. Several remarkable advantages of the use of the electrochemical method are also described.

Palladium-catalyzed electrochemical iodination and one-pot arylation of arylpyridines are described. Ortho-selective C-H iodination proceeded via dual activation of each substrate by a palladium catalyst and an electrode. Various aryl groups were introduced at the ortho positions of arylpyridines by ON/OFF switching of two different catalytic cycles using the same palladium catalyst in a one-pot fashion.

Direct evidence: The existence of methoxy radical species formed during an anodic oxidation in MeOH on a boron‐doped diamond (BDD) electrode was confirmed by ESR spectroscopy. Effective production of a neolignan, licarin A, was accomplished by the BDD‐mediated anodic oxidation protocol (see picture).

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