Imine containing C2-Symmetric chiral half sandwich ?6-p-cymene-Ru(II)- phosphinite complexes: Investigation of their catalytic activity in the asymmetric transfer hydrogenation of ketones

New chiral C-2-symmetric bis(phosphinite) ligands containing imine group were synthesized from 1-({[(1R,2R)-2-{[(2-hydroxynaphthalen-1-yl)methylidene] amino}cyclohexyl]- imino}methyl)- naphthalen-2-ol and two equivalents of Ph2PCl, (i-Pr)(2)PCl or (Cy)(2)PCl, in high yields. Binuclear C-2-symmetric half sandwich eta(6)-p-cymene-Ru(II) complexes of the chiral phosphinite ligands were synthesized by treating of [Ru(eta(6)-p-cymene)(mu-Cl)Cl](2) with the phosphinites in 1:1 M ratio in CH2Cl2. Their catalytic activities in asymmetric transfer hydrogenation (ATH) were investigated for the reaction of acetophenone derivatives with isopropyl alcohol. The corresponding optically active secondary alcohols were obtained in excellent levels of conversion (96-99%) and moderate enantioselectivity (up to 60% ee). Among three complexes investigated, complex 4 was the most efficient one. (C) 2019 Elsevier B.V. All rights reserved.