A variety of biarylbisphosphine-based ligands for ruthenium have been used to catalyze the asymmetric hydrogenation of beta-dicarbonyl systems. The method of preparation of the catalyst system plays an important role in the stereochemical outcome of the reaction as well as the reaction conditions required. The mechanism of the reaction has not been fully elucidated, but some insight has been gained. (C) 1997 Published by Elsevier Science Ltd.