Preparation method of midazolam intermediate defluoro impurity

The invention relates to the technical field of organic synthesis, and provides a preparation method of a midazolam intermediate defluoro impurity. The method comprises the following steps of: dissolving a midazolam intermediate in an organic solvent, adding Lewis acid and a reducing agent for reaction, performing extraction and chromatography on reaction liquid to obtain a crude defluoro impurity, and salifying the crude defluoro impurity with maleic acid to obtain the high-purity defluoro impurity. According to the synthesis method provided by the invention, the midazolam intermediate defluoro impurity can be obtained only through one-step reaction, and the synthesis method has a great promotion effect on optimization of production process parameters of midazolam, deep research on related substances of midazolam, improvement of the medication safety, reliability and stability of related preparations, and quality control in the production process of raw material medicines. 本发明涉及有机合成技术领域，提供了一种咪达唑仑中间体脱氟杂质的制备方法