Chiral β-Amino Alcohols as Ligands for the Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation of N-Phosphinyl Ketimines

Abstract

Some chiral β-amino alcohols have been evaluated as potential ligands for the ruthenium-catalyzed asymmetric transfer hydrogenation (ATH) of N-phosphinyl ketimines in isopropyl alcohol. The ruthenium complex prepared from [RuCl2(p-cymene)]2 and (1S,2R)-1-amino-2-indanol has shown to be an efficient catalyst for the ATH of several N-(diphenylphosphinyl)imines, affording the reduction products in very good isolated yields and enantiomeric excesses up to 82%. The inherent rigidity of the indane ring system present in the ligand seems to be very important to achieve good enantioselectivities.

Keywords

• N-(diphenylphosphinyl)imine
• asymmetric transfer hydrogenation
• ruthenium catalyst
• β-amino alcohol
• isopropyl alcohol