Chloro[(R)-(-)5,5μ-bis[bis(3,5-di-tert-butyl-4-methoxyphenyl)phosphino]-4,4μ-bi-1,3-benzodioxole](p-cymene)ruthenium(II) chloride

Biaryl bisphosphine ligand with narrow dihedral angle. The DTBM SEGPHOS ligand, as the ruthenium complex, gives superior enantioselectivity and diastereoselectivity through dynamic kinetic resolution in the asymmetric hydrogenation of a-substituted-β-ketoesters useful in the synthesis of carbapenum antibiotics.