Tunable Dehydrogenative Amidation versus Amination Using a Single Ruthenium-NHC Catalyst

Mixed N-heterocyclic carbene (NHC)/phosphine complexes
of the type [RuCl­(p-cymene)­(bimy)­(PPh3)]­PF6 (bimy = benzimidazolin-2-ylidene) have been synthesized
and fully characterized. Complex 1 bearing the 1,3-dibenzylbenzimidazolin-2-ylidene
ligand is able to selectively catalyze both dehydrogenative amidation,
mono-, and diamination (N-alkylation) through coupling
of simple alcohols with amines effectively yielding a range of amides
and secondary and tertiary amines. Selectivity is achieved by controlling
the fate of the common hemiaminal intermediate, which in turn can
be simply influenced by the choice of base and solvent.