| 摘要 |
A process for increasing the diastereoisomeric ratio (B/A+B), wherein B is the more apolar and A is the more polar of two diastereoisomers, of a mixture of diastereoisomers of a compound of formulathe diastereoisomers being with respect to the carbon atom marked with a star in formula I, comprising treating a mixture of diastereoisomers of a compound of formula I with alcohol and water and isolating the precipitated compound of formula I in an increased diastereoisomeric ratio (B/A+B) of 0.5 to 0.6.
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