Selective Room-Temperature Hydrogenation of Amides to Amines and Alcohols Catalyzed by a Ruthenium Pincer Complex and Mechanistic Insight

We
report a room-temperature protocol for the hydrogenation of
various amides to produce amines and alcohols. Compared with most
previous reports for this transformation, which use high temperatures
(typically, 100–200 °C) and H2 pressures (10–100
bar), this system proceeds under extremely mild conditions (RT, 5–10
bar of H2). The hydrogenation is catalyzed by well-defined
ruthenium-PNNH pincer complexes (0.5 mol %) with potential dual modes
of metal–ligand cooperation. An unusual Ru-amidate complex
was formed and crystallographically characterized. Mechanistic investigations
indicate that the room-temperature hydrogenation proceeds predominantly
via the Ru–N amido/amine metal–ligand cooperation.