TEMPO-Mediated Electrochemical N-demethylation of Opiate Alkaloids

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N-demethylation of opiates is a key step in the semi-synthesis of opioid medicines. A TEMPO-mediated electrochemical method for N-demethylation of opiates is described which makes use of porous glassy carbon electrodes in a simple batch cell or a flow reactor. N-demethylation is shown for opiates including thebaine, codeine, morphine and oxycodone. Electrolysis is performed at a preparative scale in aqueous solvent at room temperature in a single step, yielding the noropiates in good isolated yields (up to 83 %).

Opioids constitute a variety of import drugs that are used against alcohol/drug dependence, constipation, and extreme pain, such as the neuropathic pain associated with diabetic patients. These drugs have a characteristic pharmacophore from which many essential opioids and related compounds are derived after downstream semi-synthetic steps. The most important step in this synthetic sequence is the rate-limiting N- demethylation that leads to the formation of intermediate "nor-opiates". This paper highlights a novel TEMPO-mediated electrochemical method for the "N- demethylation" of opiates using a homemade batch cell with low-cost porous glassy carbon electrodes. Our method provides a more efficient, economical , scalable, and greener method for the production of valuable pharmaceutical building blocks. 

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