| 摘要 |
<p>The present invention concerns a process for the manufacture of the S-enantiomer of a compound of formula (I) wherein the variables are as defined in the specification and claims, comprising the steps of (A) separating a racemic compound of formula (II) wherein R', R"and R'" and Y are as defined above and Z is Q; or is halogen, amino, carboxy (-COOH); into the enantiomers and collecting the S-enantiomer; (B) if Z is other than Q, converting the S-enantiomer of formula (II) from step (A) to a S- enantiomer of formula (I); (C) racemizing the R-enantiomer of formula (II) from step (A) in a reaction medium comprising a base and an aprotic organic solvent at a temperature of from 30°C to 150°C, and (D) subjecting the racemate from step (C) to a further manufacturing cycle comprising step (A) and optionally (B). Accordingly, a cyclic process is provided, wherein the undesired enantiomer of a first enantiomer separation step is racemized and then phased in a further enantiomer separation step.</p> |
