Investigation of catalytic activity of ferrocene based bis(phosphinite) Ru(II) benzene complexes in asymmetric reduction of ketones

Abstract

Chiral substances are very important in industry and academic works. The most elegant approach for the synthesis of such compounds is via asymmetric catalytic process. Asymmetric catalysis has been developed very rapidly in the past three decades. Chiral bidentate phosphinite ligands easily coordinate to a metal through unpaired electron pairs on both phosphorus atoms and they have different binding properties (monodentate, bidentate and bridged), and thus they are attracting considerable attention. Transition metal complexes of ferrocene containing chiral ligands have been active catalysts in various asymmetric transformations. Among these reactions, hydrogenation, hydrosilylation, cross-coupling reactions and aldol condensation are commonly used in organic synthesis. Use of ferrocenyl phosphinites as ligands in ruthenium(II)-catalyzed transfer hydrogenation is not so extensive.In the present study, the chiral C2-symmetric ferrocenylaminoalcohols were prepared from the chiral compounds having different R-groups. Then, the new C2-symmetric bis (phosphinite) compounds were synthesized by the reaction of these aminoalcohols with Ph2PCl or iPr2PCl. Finally, use of these transition metal complexes as catalysts in asymmetric transfer hydrogenation reactions of ketones was investigated.