Ruthenium Catalysts for Hydrogen Transfer Reactions

The development of well-defined homogeneous catalysts is a current target for achieving selective catalytic organic transformations under mild reaction conditions. Selective and productive catalysts are prepared through a fine tuning of the stereoelectronic properties of the ligands that display a cooperative effect with the metal. The transfer hydrogenation of carbonyl compounds is a cost-effective and environmentally benign approach for the synthesis of alcohols using 2-propanol or formic acid as hydrogen donors. This process that entails a C-H activation opens the way for the reverse alcohol oxidation, dehydrogenation and borrowing hydrogen reactions involving alcohols. This presentation deals with the preparation and reactivity of ruthenium complexes containing bi- and tridentate ligands which can find application in the catalytic reduction of carbonyl compounds (i.e. 5-HMF, ethyl levulinate, flavanones), Oppenauer-type alcohol oxidation, amine alkylation and light induced transfer hydrogenation (Figure 1).