Chemoselective Hydrogenation of Aldehydes under Mild, Base-Free Conditions: Manganese Outperforms Rhenium
Mathias Glatz1, Berthold Stöger1, Daniel Himmelbauer1
1Institute of Applied Synthetic Chemistry and X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
Abstract:
Several hydride Mn(I) and Re(I) PNP pincer complexes were applied as catalysts for the homogeneous chemoselective hydrogenation of aldehydes. Among these, [Mn(PNP-iPr)(CO)2(H)] was found to be one of the most efficient base metal catalysts for this process and represents a rare example which permits the selective hydrogenation of aldehydes in the presence of ketones and other reducible functionalities, such as C=C double bonds, esters, or nitriles. The reaction proceeds at room temperature under base-free conditions with catalyst loadings between 0.1 and 0.05 mol% and a hydrogen pressure of 50 bar (reaching TONs of up to 2000). A mechanism which involves an outer-sphere hydride transfer and reversible PNP ligand deprotonation/protonation is proposed. Analogous isoelectronic and isostructural Re(I) complexes were only poorly active.
More Related Videos
Related Concept Videos
Hydrogen Bonds
Hydrogen Bonds Control the World!
Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are unequally shared....
Hydrogen Bonds
Base-Promoted α-Halogenation of Aldehydes and Ketones
IUPAC Nomenclature of Aldehydes
Structures of Aldehydes and Ketones
In aldehydes (Figures 1a and 1b), the...
Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...


