Amide as ligands for asymmetric transfer hydrogenation of prochiral ketones by ruthenium catalyst

Abstract

Chiral amide ligands were synthesized from L-proline and cinchonine and their application to asymmetric transfer hydrogenation of prochiral ketones was studied. Transfer hydrogen reaction catalyzed by proline based amino amide hydrochlorides was carried out in aqueous HCOONa while sulfonamide derived from cinchonin was carried out in iso-propanol containing NaOH using [RuCl2(p-cymene)] 2 as catalyst. The ATH of Chiral amino amide hydrochlorides reaction yielded excellent conversion rates of > 99% with good enantioselectivities (up to 76.9% ee) with water as solvent. The reaction of the substituted acetophenone showed that the enantioselectivity was not significantly affected by the type of substituent on aryl but also by alkyl.