Alkoxy substituted MeO-BIPHEP-type diphosphines ligands for asymmetric hydrogenation of aryl ketones

In this paper, a series of optically active MeO-BIPHEP-type ligands, (S)-6,6′-dimethoxy-2,2′-bis(di-p-alkoxyphenylphosphine)-1,1′-biphenyl were synthesized and used to prepare the ruthenium complex. The effects of para-substituted were observed, the results showed that the ruthenium catalysts [diphosphine RuCl2 diamine] containing both t-Bu and i-Pr substitutions have better activities and enantioselectivities than the non-substituted ruthenium catalysts in the asymmetric hydrogenation of acetophenone.