Recent progress in tartaric acid‐modified Raney nickel system for enantio‐differentiating hydrogenation

Tartaric acid‐modified Raney nickel (TA‐MRNi) is an enantio‐differentiating catalyst for hydrogenation of ketones. The stereochemical models explaining the enantio‐differentiation of β‐ketoester and 2‐alkanone were unified as an extended stereochemical model by the experimental supports. Based on this new model, a working hypothesis to improve the enantiomeric excess (ee) of the β‐ketoester/TA‐MRNi system was developed, and the ee was improved to 96%. By further fine tuning of this system, almost perfect enantio‐differentiation resulting in over 98% ee was achieved.