Ru-Catalyzed Enantioselective Hydrogenation of Diaryl 1,4-Diketones: Synthesis of Chiral 1,4-Diarylbutane-1,4-Diols

Asymmetric hydrogenation of diaryl 1,4-diketones was achieved by using trans-RuCl₂[(S)-BINAP)][(S)-Daipen] as the catalyst and the reaction gave rise to excellent enantio- and diastereoselectivities (up to >99% ee and de). This procedure provides a convenient and efficient synthetic method for chiral 1,4-diarylbutane-1,4-diols, which are important intermediates for a variety of chiral auxiliaries and ligands.

Ru-Catalyzed Chemo- and Enantioselective Hydrogenation of 2,4-Pentadien-1-ones: Synthesis of Chiral 2,4-Pentadien-1-ols

The asymmetric hydrogenation of 2,4-pentadien-1-ones has been achieved by using trans-RuCl₂[(R)-XylylSunPhos][(R)-Daipen] as a catalyst under basic conditions. This hydrogenation demonstrated exclusive C1-carbonyl selectivity, and thus the conjugated 2,4-diene motifs remained untouched, which provides a synthetically useful method for various chiral 2,4-pentadien-1-ols.

Ru-Catalyzed Chemo- and Enantioselective Hydrogenation of β-Diketones Assisted by the Neighboring Heteroatoms

A highly chemo- and enantioselective hydrogenation of β-diketones was achieved by using [Ru(benzene)(S)-SunPhosCl]Cl for consistency in THF. The neighboring heteroatoms played important roles in guaranteeing the reactivity and controlling the chemoselectivity. These results suggested a potential approach for the clean and facile synthesis of functionalized chiral β-hydroxy ketones, which could otherwise be prepared through much less step-economic transformations.

Highly Diastereo- and Enantioselective Access to syn-α-Amido β-Hydroxy Esters via Ruthenium-Catalyzed Dynamic Kinetic Resolution-Asymmetric Hydrogenation

Dynamic kinetic resolution (DKR) of racemic aryl α-amino β-ketoesters via Ru-diphosphine-catalyzed asymmetric hydrogenation was realized at 70 °C under 50 atm of hydrogen, affording syn α-amido β-hydroxy esters in high yields (up to 96%) with high reactivity (TON up to 940) and diastereo- and enantioselectivities (up to 99:1 dr, 98% ee). These hydrogenation products provide valuable chiral synthons in many natural products and pharmaceuticals. Gram-scale DKR asymmetric hydrogenation (DKR-AH) was also performed with retained reactivity and stereoselectivity, revealing the synthetic utility of this method.

Copper-catalyzed asymmetric hydrogenation of 2-substituted ketones via dynamic kinetic resolution

A new class of tunable heterophosphole dimeric ligands have been designed and synthesized. These ligands have enabled the first examples of Cu-catalyzed hydrogenation of 2-substituted-1-tetralones and related heteroaryl ketones via dynamic kinetic resolution, simultaneously creating two contiguous stereogenic centers with up to >99 : 1 dr and 98 : 2 er. The ligand-Cu complexes were isolated and characterized by single crystal X-ray, and DFT calculations revealed a novel heteroligated dimeric copper hydride transition state.