Ruthenium-Catalyzed Deuteration of Alcohols with Deuterium Oxide

The
catalytic properties of a series of ruthenium complexes for
H/D exchange between D2O and alcohols were studied. The
catalytic activity of the ruthenium complexes and the regioselectivity
of the H/D exchange reactions were found to be dependent on the auxiliary
ligands. While ruthenium η6-cymene complexes such
as [(η6-cymene)­RuCl­(NH2CH2CH2NTs)]­Cl, (η6-cymene)­RuCl2/NH2CH2CH2OH, and (η6-cymene)­Ru­{(S,S)-NHCHPhCHPhNTs} catalyzed regioselective
deuteration of alcohols with D2O at the β-carbon
positions only, octahedral ruthenium complexes such as RuCl2(2-NH2CH2Py)­(PPh3)2 (2-NH2CH2Py = 2-aminomethylpyridine) and RuCl2(NH2CH2CH2NH2)­(PPh3)2 catalyzed regioselective H/D exchange reactions
of D2O with alcohols at both the α- and β-carbon
positions of alcohols. The H/D exchange reactions proceed through
reversible dehydrogenation of alcohols and hydrogenation of carbonyl
compounds involving hydride species and H/D exchange among D2O and carbonyl and hydride species. The different regioselectivities
of the H/D exchange reactions can be related to the relative ease
of H/D exchange of ruthenium hydride intermediates with D2O.