Asymmetric transfer hydrogenation reaction in water: Comparison of chiral proline amide/amine ruthenium(II) complexes

• Chiral proline-derived chiral amide/diamine ligands 2 and 3 were prepared and used for ATH.
• Chiral proline amide ligands having more acidic N–H gave better yields as compared with the corresponding amine derivatives.
• The bulk of the aryl substituents on the ligand increased the enantioselectivity.

Chiral proline amide/amine ligands (2, 3), synthesized by multi-step reaction starting from l-proline (1), were evaluated as catalyst generated in situ from [RuCl2(p-cymene)]2 for asymmetric transfer hydrogenation of aromatic ketones in the presence of sodium formiate and sodium dodecyl sulfate (SDS). The results revealed that efficiencies and enantioselectivities strongly depend on the N-substituents.

Asymmetric transfer hydrogenation of ketones using chiral proline amide/amine ligands.Figure optionsDownload as PowerPoint slide