Asymmetric Transfer Hydrogenation of Aryl Heteroaryl Ketones using Noyori?Ikariya Catalysts

A range of ketones flanked by a combination an aromatic and heterocyclic ring (furan, thiophene, N-methylimidazole) were reduced under asymmetric transfer hydrogenation (ATH) conditions. Using [(arene)Ru(TsDPEN)Cl] precatalysts, including tethered derivatives, the reduction enantioselectivity was high (up to 99 % ee) in cases where contained ortho-substituent. The is influenced steric electronic factors which for furan thiophene series, follow literature precedents. In case N-methylimidazole-containing ketones, unexpected switch took place upon variation opposing group. Pyrrole- containing resistant reduction. This study demonstrates hindered conversion ee, using Noyori-Ikariya catalysts.