RuPHOX-Ru-Catalyzed Selective Asymmetric Hydrogenation of Exocyclic α,β-Unsaturated Pentanones

A RuPHOX-Ru catalyzed selective asymmetric hydrogenation of exocyclic alpha,beta-unsaturated ketones has been developed, furnishing the corresponding chiral exocyclic allylic alcohols in high yields and with up to >99.5% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 10000 S/C) without any loss in reaction activity and enantioselectivity. The resulting hydrogenated products could be easily transformed to several biologically active compounds with high asymmetric performance. The asymmetric protocol provides an efficient methodology for the synthesis of chiral exocyclic allylic alcohols.