| 摘要 |
Enantiomers of 1-(4-chloro phenyl) -2-(4-((4-fluoro phenyl)methyl)-1-piperidyl) ethanol (I) are sepd. by the following process: Racemic (I) is reacted with S(-) 1-phenyl ethyl isocyanate (S-II) to form a mixt. of diastereoisomeric carbamates, A and B. These are sepd. by fractional crystallisation and carbamate A is treated with lithium aluminium hydride (LAH) to give pure (+) (I). The mixt. of carbamates obtained from the sepn. mother liquors, in which B predominates, is treated with LAH to give impure (-) (I). This is treated with R(+) 1-phenyl ethyl isocyanate (R-II) to give a mixt. of two carbamates, A' and B'. The A' isomer is purified by fractional crystallisation and treated with LAH to give pure (-) (I). USE - (I) is a known cerebral anti-ischemic agent, described in EP 0 109 317.
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