Asymmetric Hydrogenation of α,β-Unsaturated Carboxylic Acids Catalyzed by Ruthenium(II) Complexes of Spirobifluorene Diphosphine (SFDP) Ligands

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Abstract

The ruthenium diacetate complexes ligated by chiral spirobifluorene diphosphines (SFDP) were very effective catalysts for the asymmetric hydrogenation of tiglic acid derivatives and α-methylcinnamic acid derivatives with high activities and excellent enantioselectivities (up to 98 % ee). The α-aryloxybutenoic acids can also be hydrogenated by these catalysts to provide the corresponding saturated α-aryloxybutanoic acids in high yields (89–93 %) and enantioselectivities (up to 95 % ee). In this reaction, the SFDP ligand with para-methyl groups on the P-phenyl rings gave the best results.

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