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The diastereoselective catalytic hydrogenation of β‐keto sulfoxides in the presence of ruthenium complexes was studied. Optically pure β‐keto sulfoxides were hydrogenated in the presence of achiral catalysts leading to moderate yields and stereoselectivities. Using chiral ruthenium catalysts such as [(R)‐MeO‐BIPHEPRuBr2] and [(S)‐MeO‐BIPHEPRuBr2], the hydrogenation proceeded in good yields with very high diastereoselectivity. Chirality at the secondary centre of the β‐hydroxy sulfoxides produced was controlled by the catalysts.

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-044Chiral Ruthenium-Catalyzed Hydrogenation of β-Keto Sulfoxides.-The diastereoselectivity of ruthenium-catalyzed reduction of β-keto sulfoxides is studied. Hydrogenation of optically active keto sulfoxide (I) in the presence of achiral ruthenium catalysts proceeds with moderate stereoselectivity, while β-hydroxy sulfoxide (II) is obtained with excellent diastereomeric excess in the presence of a planar chiral biphenyl ligand (MeO-biphep). It is shown that the diastereoselectivity of reduction is governed mainly by the catalyst chirality, while the chirality of sulfoxide plays a minor role. Thus, reduction of racemic β-keto sulfoxides (IV) in the presence of a chiral ruthenium catalyst followed by desulfurization provides alcohols (VI) in moderate to high optical purity.