| 摘要 |
<p>Provided is a method of general applicability of epimerizing a vitamin-D analog having an asymmetric allylic carbon atom at the C-24 position, which comprises the steps of: a) esterifying the hydroxyl group on the asymmetric allylic carbon atom at the 24 position with an esterifying agent, b) contacting a solution of the ester in a solvent with an epimerization-active solid, whereby the ester is epimerized, and c) hydrolysing the epimerized ester to obtain a mixture of C-24 epimers having a hydroxyl substituent on the asymmetric allylic carbon at position 24. The method is of particular utility in making calcipotriene.</p> |
