One-Pot Palladium-Catalyzed Borrowing Hydrogen Synthesis of Thioethers

Palladium on magnesium oxide is able to allow a one-pot reaction to synthesize thioethers from thiols and aldehydes formed in situ from the respective alcohol by means of a borrowing hydrogen method. The reaction is initiated by dehydrogenation of the alcohol to give a palladium hydride intermediate and an aldehyde. The latter reacts with a thiol involving most probably the intermediacy of a thionium ion RCHS+R, which can be reduced in situ by the metal hydride to afford thioethers.