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.
提供了一种适用于表征
维生素D类似物的一般方法,其中在C-24位置具有不对称烯丙基碳原子,包括以下步骤:a)用酯化剂对24位置的不对称烯丙基碳原子上的羟基进行酯化,b)将酯的溶液与溶剂中的表征活性固体接触,从而对酯进行表征,c)
水解表征后的酯,以获得在24位点上具有羟基取代基的C-24表征体混合物。该方法在制备
钙醇
三烯酮中具有特殊效用。