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The most challenging step in the preparation of many opioid antagonists is the selective N-demethylation of a 14-hydroxymorphinan precursor. This process is carried out on a large scale using stoichiometric amounts of hazardous chemicals like cyanogen bromide or chloroformates. We have developed a mild reagent- and catalyst-free procedure for the N-demethylation step based on the anodic oxidation of the tertiary amine. The ensuing intermediates can be readily hydrolyzed to the target nor-opioids in very good yields.