Cobalt Complexes as Efficient Cooperative Catalysts for Transfer Hydrogenation

Cobalt complexes of amide-based ligands appended with protonated heterocyclic rings are utilized as the earth-abundant catalysts for the transfer hydrogenation of assorted carbonyl compounds using isopropanol as the hydrogen source. The most successful complex illustrated remarkable catalytic performance towards a wide range of aldehydes and ketones, quantitatively yielding primary and secondary alcohols as the products, respectively. The catalysis scope also included a few biologically relevant substrates such as furfural, vanillin, ortho-vanillin, coumarin and chalcone. The substrate binding, Hammett, kinetic and DFT studies provided the mechanistic insights.