Highly stereoselective asymmetric hydrogenation of 2-benzamidomethyl-3-oxobutanoate catalysed by cationic binap–ruthenium( II ) complexes

Highly diastereoselective hydrogenation of methyl 2-benzamidomethyl-3-oxobutanoate has been accomplished by using [Rul{(R)-binap}(p-cymene)]I and corresponding complexes of derivatives of binap as catalyst, giving methyl (2S,3R)-2-benzamidomethyl-3-hydroxybutanoate, a versatile intermediate for the synthesis of β-lactam antibiotics, in up to 98% diastereoisomeric excess and 99% enantiomeric excess.