Challenging Task of Ni-Catalyzed Highly Regio-/Enantioselective Semihydrogenation of Racemic Tetrasubstituted Allenes via a Kinetic Resolution Process

Abstract

The first earth-abundant transition metal Ni-catalyzed highly regio- and enantioselective semihydrogenation of racemic tetrasubstituted allenes via a kinetic resolution process as a challenging task was well established. This protocol furnishes expedient access to a diversity of structurally important enantioenriched tetrasubstituted allenes and chiral allylic molecules with high regio-, enantio-, and Z/E-selectivity. Remarkably, this semihydrogenation proceeded with one carbon–carbon double bond of allenes, which was regioselective complementary to the Rh-catalyzed asymmetric version. Deuterium labeling experiments and density functional theory (DFT) calculations were carried out to reveal the reasonable reaction mechanism and explain the regio-/stereoselectivity.

Nickel-catalyzed asymmetric hydrogenation for the preparation of α-substituted propionic acids

“…1b ). Recently, nickel catalysts have received much attention when employed in asymmetric hydrogenation, particularly by Hamada 50 , 51 , Zhou 52 – 55 , Chirik 56 , Zhang 57 – 61 , our group 62 – 66 , and other research groups 67 – 72 . However, perhaps owing to the lower steric hindrance of disubstituted olefins, which complicates the control of stereoselectivity in the reaction, the majority of studies have concentrated on tri- and tetra-substituted olefins 50 – 72 .…”