Synthesis of R - -methyl 3-hydroxypentanoate using BisP—Ru

In a glass autoclave equipped with a magnetic stirrer bar were placed BisP -RuBr2 (52 mg), methyl 3-oxopentanoate (10.7 g), and degassed methanol/ water (10/1) 200 mL under an argon atmosphere. 

Then argon gas was replaced with hydrogen. The hydrogenation was performed at 70 °C under 6kg/cm2 of hydrogen for 10 hours. 

The solvent was removed under reduced pressure and the residue was purified by chromatography on silica gel (chloroform acetone = 3 1) to afford ( )-(—)-methyl 3-hydroxypentanoate (10.4 g, 96%, 98% ee) as a colourless oil. 

The asymmetric hydrogenation with BisP RuBr2 may be applied to a wide range of (3-ketoesters, (3-kctoamidcs, and (3-ketophosphonates. Table 9.2 shows typical examples. 

4/ )-2-AZANORBORNYLMETHANOL, AN EFFICIENT LIGAND FOR RUTHENIUM CATALYSED ASYMMETRIC TRANSFER HYDROGENATION OF AROMATIC KETONES 

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