Ruthenium catalysts and method for making same

The present invention relates to the field of asymmetric hydrogenation and, more particularly, to the use of novel Ru(II) chiral catalysts for the asymmetric hydrogenation of substrates which, as a result of their weak donor capability and of their hindered structures, have proved heretofore very difficult or impossible to hydrogenate. A catalyst of ruthenium (II) comprising bidentate phosphine ligands is described which is obtained by a process that comprises treating equimolar amounts of an appropriate Ru complex and a bidentate diphosphine ligand with an acid of the formula H-Anion, wherein the anion is a non-coordinating anion, said acid being used in a ratio of 1 molar equivalent per mole of Ru complex and the treatment being carried out in a non-coordinating or weakly coordinating medium, under an oxygen-free atmosphere. Said catalyst is useful for the preparation of the preferred isomer of the Hedione®, having the configuration (+)-(1R)-cis, and of many other substrates comprising highly hindered carbon-carbon double bonds.