Asymmetric transfer hydrogenation of ketones by N,N-containing quinazoline-based ruthenium(II) complexes

Abstract

The novel set of quinazoline-based chiral ligands was synthesized starting from optically pure amino acids. Coordination with RuCl2(PPh3)dppb gave ruthenium(II) N-heterocyclic complexes 4b–d. The structure of complex 4b was fully illuminated by X-ray crystallography. The steric environment of these chiral ruthenium complexes 4b–d was evaluated in asymmetric transfer hydrogenation (ATH) of prochiral ketones in the presence of NaOiPr by using 2-propanol as the hydrogen source and solvent. The resultant catalytic system can achieve very good enantioselectivities (up to 91%) and high yields (up to 99%).