SYNTHESIS OF AXIALLY DISSYMMETRIC BIPHENYLBISPHOSPHINE LIGANDS, BIMOPS AND ASYMMETRIC HYDROGENATIONS OF β-KETO ESTER AND α, β-UNSATURATED CARBOXYLIC ACID CATALYZED BY THEIR RUTHENIUM (II) COMPLEXES

Axially dissymmetric biphenylbisphosphine ligands, BIMOP (1a) and p-MeO-BIMOP (1b) have been newly designed and prepared. The ruthenium (II) complexes of (R)-1a and 1b proved to be excellent catalysts in asymmetric hydrogenations of methyl 3-oxobutanoate and tiglic acid affording (R)-methyl 3-hydroxybutanoate of 95-99 % ee and (R)-2-methylbutyric acid of 86-91 % ee, respectively.