Preparation method of sofosbuvir impurity

The invention discloses a preparation method of a sofosbuvir impurity, the sofosbuvir impurity is an impurity SM1-Q7, and the sofosbuvir impurity is prepared by one of the following two synthesis routes. The method has the advantages of easily available raw materials, mild reaction conditions and simple operation, and the obtained SM1-Q7 has good purity and meets the requirements of research and control of sofosbuvir impurities. 本发明公开了索非布韦杂质的制备方法，所述索非布韦杂质为杂质SM1-Q7，其制备采用下述两种合成路线的其中一种。本发明原材料易得、反应条件温和、操作简单，所得SM1-Q7纯度较好并符合索非布韦杂质研究和控制的要求。