Further 'tethered' Ru(II) catalysts for asymmetric transfer hydrogenation (ATH) of ketones; the use of a benzylic linker and a cyclohexyldiamine ligand

Abstract The synthesis and characterisation of two new Ru(II) catalysts for the asymmetric transfer hydrogenation (ATH) of ketones is described. In the case of 4 , the novelty lies in the use of a benzyl tethering group between the asymmetric ligand part (TsDPEN) and the η 6 -arene ring, which increases the complex rigidity. For 5 , the use of a cyclohexyldiamine as a chiral ligand is described for the first time. In the ATH of ketones in formic acid/triethylamine, alcohols with ees of up to 97% were formed.