Preparation method of betamethasone acetate

The invention relates to a preparation method of betamethasone acetate, which specifically comprises the following steps: by taking DMSO (dimethylsulfoxide) as a solvent, reacting betamethasone with acetic anhydride under the catalysis of sodium acetate to form ester, and after the reaction is finished, carrying out elutriation on the reaction liquid to obtain the betamethasone acetate. The method has the advantages of low cost, high yield, no production of nitrogenous wastewater, greenness and environmental protection, and is suitable for industrial production requirements. 本发明涉及一种倍他米松醋酸酯的制备方法，具体包括，以DMSO为溶剂，倍他米松与醋酸酐经醋酸钠催化反应成酯，反应结束后，将反应液水析，得到倍他米松醋酸酯。本发明成本低、收率高、不产生含氮废水，绿色环保，适合工业化生产要求。