Optically active β-ketoiminato cobalt(II) complexes as highly efficient catalysts in enantioselective borohydride reduction of ketones, imines, and α,β-unsaturated carboxylates

A new class of cobalt complexes with optically active N,N′-ethylenebisketoiminato ligands was synthesized, and one of them was fully characterized by X-ray crystallographic analysis. These cobalt(II) complexes proved to be efficient catalysts in enantioselective borohydride reduction of aryl ketones, phosphinyl imines, and β,β-disubstituted α,β-unsaturated carboxylates. It was found that the enantiofacial discrimination in the borohydride reduction was influenced by the structure of the diphenylethylenediamine moiety of the cobalt complex catalysts.