Abstract: A method for preparing analogues of C1,C24-dihydroxy-vitamin D is disclosed. Especially the method for preparing calcipotriol and tacalcitol from a starting material of Vitamin D2 is disclosed here. Calcipotriol (compound 1(a)) and tacalcitol (compound 1(b)) can be synthesized by the method of the present invention. Moreover, only nine steps are needed for the synthesis of calcipotriol using the method. Likewise, only ten steps are needed for the synthesis of tacalcitol by the present method. Hence, the present method, with less process steps and higher yields, represents an improvement over the conventional methods.

Abstract: Since the C-24 of the vitamin D derivatives having C-24 hydroxyl branch is a chiral center, there are two epimers, i.e. C-24R hydroxyl and C-24S hydroxyl, that can be found. However, only the diastereomer with C-24S hydroxyl is biologically active. A method for selectively enzymatically esterifying or selectively enzymatically solvolyzing a mixture of epimers of the C-24 hydroxyl vitamin D derivatives is disclosed here. The method can be used to separate these two diastereomers from a mixture of the epimers thereof for purification process. In addition, the method can be used for isomerising the C-24R hydroxyl epimer for further recycling purposes.