Efficient synthesis of chiral phenethylamines: preparation, asymmetric hydrogenation, and mild deprotection of ene-trifluoroacetamides

A mild and efficient route to enantioenriched aryl alkyl amines from ketones has been developed. The first successful synthesis and asymmetric hydrogenation of ene-trifluoroamides from oximes gave highly enantioenriched trifluoroacetamides (94–98% ee). The corresponding phenethyl amides are liberated under mild conditions (K2CO3, MeOH/H2O). In addition, a new application of Josiphos ligands toward the asymmetric hydrogenation of both ene-acetamides and ene-trifluoroacetamides was discovered.