Highly enantioselective catalytic hydrogenation of a 5-amino-3,5-dioxopentanoic ester

The highly enantioselective hydrogenation of methyl 4-tert-butylcarbamoyl-3-oxo-butyrate to the corresponding secondary alcohol, representing an interesting chiral building block, for example, for the synthesis of statins, has been investigated in the presence of homogeneous chiral Rh(I) and Ru(II) complexes bearing phosphine ligands. The highest enantioselectivity (up to 96%) was achieved with a [Ru((R)-BINAP)(p-cymene)Cl]Cl complex (sub./cat. ratio 100:1, 5 bar H2, rt, MeOH).