| 摘要 |
<p>Process for the preparation of enantiomerically pure (<Italic>S</Italic>)- or (<Italic>R</Italic>)-4-halo-3-hydroxybutyrates of formula
<Chemistry id="chema01" num="0001"><Image id="ia01" he="19" wi="115" file="IMGA0001.TIF" imgContent="chem" imgFormat="TIFF" /></Chemistry> wherein R<Sup>1</Sup> is CH<Sub>2</Sub>X, CHX<Sub>2</Sub> or CX<Sub>3</Sub> and X independently represents Cl and/or Br and wherein R<Sup>2</Sup> is C<Sub>1-6</Sub>-alkyl, C<Sub>3-8</Sub>-cycloalkyl, aryl or aralkyl, each aryl or aralkyl being optionally further substituted with one or more C<Sub>1-4</Sub>-alkyl groups and/or halogen atoms, by asymmetric hydrogenation of 4-halo-3-oxobutyric acid esters of formula
<Chemistry id="chema02" num="0002"><Image id="ia02" he="17" wi="110" file="IMGA0002.TIF" imgContent="chem" imgFormat="TIFF" /></Chemistry> wherein R<Sup>1</Sup>, R<Sup>2</Sup> and X are as defined above
in the presence of a catalyst of a ruthenium complex comprising a chiral ligand of the formula
<Chemistry id="chema03" num="0003"><Image id="ia03" he="40" wi="106" file="IMGA0003.TIF" imgContent="chem" imgFormat="TIFF" /></Chemistry></p> |
