Enantioselective hydrogenation of imines using a diverse library of ruthenium dichloride(diphospbine)(diamine) precatalysts

A range of aromatic and cyclic imines were subjected to asymmetric hydrogenation with catalysts derived from complexes of the type RuCl2(diphosphine)(diamine). Good to high enantioselectivities were observed. For each imine, a library of chiral complexes based on different diphosphine and diamine combinations was screened. A different combination of diphosphine and diamine was required each time to obtain the optimum enantioselectivity.