Chiral β-amino alcohols as ligands for the ruthenium-catalyzed asymmetric transfer hydrogenation of N-phosphinyl ketimines

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.

This work was generously supported by the Spanish Ministerio de Ciencia e Innovación (MICINN; Grant No. CONSOLIDER INGENIO 2010, CSD2007-00006, CTQ2007-65218, and CTQ11-24151) and the Generalitat Valenciana (PROMETEO/2009/039 and FEDER). Óscar Pablo thanks the Spanish Ministerio de Educación for a predoctoral fellowship (Grant No. AP2008-00989).