Iridium-catalyzed chemoselective asymmetric hydrogenation of conjugated enones with ferrocene-based multidentate phosphine ligands

A series of novel and readily prepared ferrocene-based multidentate phosphine ligands (f-PNNO) have been developed and successfully used in iridium-catalyzed enantioselective 1,2-reduction of α,β-unsaturated ketones, delivering chiral allylic alcohols in high yields and high enantioselectivities (up to 99% yield and up to 99% ee). Furthermore, the gram scale reaction proceeded very smoothly with 0.001 mol% catalyst loading, which indicated that the newly developed Ir/f-PNNO catalytic system has excellent activity in asymmetric hydrogenation of conjugated enones.