Catalytic asymmetric reductive amination of ketones via highly enantioselective hydrogenation of the CN double bond

Abstract

We describe a convenient, chemoselective asymmetric reductive amination procedure for the conversion of ketones to chiral hydrazines and amines. The key step in the three-step process is enantioselective DuPHOS-Rh-catalyzed hydrogenation of the CN double bond of N-acylhydrazones. Detailed optimization studies revealed the effect of solvent, temperature, and the N-acyl group on the enantioselectivity and catalytic efficiency of the reaction. The reduction products, N-acylhydrazines, were converted to hydrazines or amines through hydrolysis or treatment with samarium(II) iodide, respectively.