Asymmetric hydrogenation of γ-branched allylamines for the efficient synthesis of γ-chirogenic amines

The efficient construction of γ-chirogenic amines has been realized via asymmetric hydrogenation of γ-branched N-phthaloyl allylamines by using a bisphosphine-Rh catalyst bearing a large bite angle. The desired products possessing different types of γ-substituents were obtained in quantitative yields and with excellent enantioselectivities (up to >99.9% ee). This protocol provided a practical method for the preparation of γ-chirogenic amine derivatives such as the famous antidepressant drug Fluoxetine (up to 50000 S/C). The mechanism calculation shows a weak interaction-promoted activation mode which is completely different from the traditional coordination-promoted activation mode in the Rh-catalyzed hydrogenation.