Chiral Benzoins via Asymmetric Transfer Hemihydrogenation of Benzils: The Detail that Matters

Dynamic Kinetic Resolution of β-Substituted α-Diketones via Asymmetric Transfer Hydrogenation

Developing innovative dynamic kinetic resolution (DKR) modes and achieving the highly regio- and enantioselective semihydrogenation of unsymmetrical α-diketones are two formidable challenges in the field of contemporary asymmetric (transfer) hydrogenation. In this work, we report the highly regio- and stereoselective asymmetric semi-transfer hydrogenation of unsymmetrical α-diketones through a unique DKR mode, which features the reduction of the carbonyl group distal from the labile stereocenter, while the proximal carbonyl remains untouched. Moreover, the protocol affords a variety of enantioenriched acyclic ketones with α-hydroxy-α'-C(sp²)-functional groups, which represent a new product class that has not been furnished in known arts. The utilities of the products have been demonstrated in a series of further transformations including the rapid synthesis of drug molecules. Density functional theory calculations and plenty of control experiments have also been conducted to gain more mechanistic insights into the highly selective semihydrogenation.

Enantioselective direct, base-free hydrogenation of ketones by a manganese amido complex of a homochiral, unsymmetrical P–N–P′ ligand

Base-free direct hydrogenation of ketones using a Mn(PNP′)(CO)₂ complex is more enantioselective than that of a related base-activated iron complex.