Ruthenium Catalyzed Direct Asymmetric Reductive Amination of Simple Aliphatic Ketones Using Ammonium Iodide and Hydrogen
Tamal Kanti Ghosh, Martin Ernst, A. Stephen K. Hashmi, Thomas Schaub
Abstract
The direct conversion of ketones into chiral primary amines is a key transformation in chemistry. Here, we present a ruthenium catalyzed asymmetric reductive amination (ARA) of purely aliphatic ketones with good yields and moderate enantioselectivity: up to 99 % yield and 74 % ee . The strategy involves [Ru(PPh 3 ) 3 H(CO)Cl] in combination with the ligand ( S,S )‐ f ‐binaphane as the catalyst, NH 4 I as the amine source and H 2 as the reductant. This is a straightforward and user‐friendly process to access industrially relevant chiral aliphatic primary amines. Although the enantioselectivity with this approach is only moderate, to the extent of our knowledge, the maximum ee of 74 % achieved with this system is the highest reported till now apart from enzyme catalysis for the direct transformation of ketones into chiral aliphatic primary amines.