Palladium on carbon-diethylamine-mediated hydrodeoxygenation of phenol derivatives under mild conditions

We have found that phenolic hydroxyl groups were readily deoxygenated via aryl sulfonate under the Pd/C-catalyzed hydrogenation conditions in the presence of diethylamine and the method could also be applicable to the hydrodeoxygenation of morphine to afford 3-deoxy-7,8-dihydromorphine. Diethylamine is not only a scavenger of the corresponding methanesulfonic acid derivative, which is produced during the reaction progress, but also a strong promoter of the Pd/C-catalyzed reduction of aryl sulfonates. This catalyst system could provide a general method for the deoxygenation of various phenol derivatives because of its mild reaction conditions, ease of handling, and no need of particular apparatus.