The invention relates to a preparation method of an activated
vitamin D3
drug CD ring intermediate. The preparation method comprises the following steps: carrying out
iodine substitution on a
diol derivative 2 to obtain a compound 3, carrying out hydroxyl reaction on the compound 3 to obtain a compound 4, carrying out Michael
addition reaction on the compound 4 to obtain a compound 5, carrying out
nucleophilic addition reaction on the compound 5 to obtain a compound 6, carrying out deprotection reaction on the compound 6 to obtain a compound 7, and carrying out oxidation reaction on the compound 7 to obtain a compound 1, namely, the activated
vitamin D3
drug CD ring intermediate (25-hydroxy Grundmann's one). The preparation method provided by the invention has the advantages that the steps are simple, the product yield is high, and massive 25-hydroxy Grundmann's one can be prepared.