Iron-Catalyzed Reductive Amination of Aldehydes in Isopropyl Alcohol/Water Media as Hydrogen Sources

Reductive amination can be carried in i-PrOH/H2O as hydrogen sources using commercially available iron carbonyl complexes. Within an aqueous alkaline environment, a hydridocarboferrate is formed and its reducing potential is exploited for hydrogenation of the imine (or iminium ion) obtained insitu from aldehydes or ketones, and primary or secondary amines in almost equimolar ratio. This completely sustainable and hydrogen-free process proceeds at 100 degrees C using Fe-3(CO)(12) as catalyst precursor under convectional heating while Fe-2(CO)(9) gave better results when the reaction was carried out under MW dielectric heating. Both enolizable and non-enolizable aldehydes may be successfully employed in reactions with aliphatic and aromatic amines.