The invention provides a preparation method of a key intermediate of a
gemfibrozil impurity A, and belongs to the technical field of
chemical synthesis. According to the invention, a brand-new synthetic
route of the
gemfibrozil impurity A is designed firstly, and efficient preparation methods of three key intermediates are provided on the basis of the brand-new synthetic
route. Specifically, the preparation method comprises the following steps: firstly, reacting with
propionyl chloride in a 1, 2-
dichloroethane environment under the
catalysis of
aluminum trichloride, and cooling, layering and
drying a product to obtain a first intermediate; taking the first intermediate as a
raw material, reacting with
benzyl bromide in a DMF (
Dimethyl Formamide) environment by taking
potassium carbonate as an acid-binding agent, collecting an organic phase, dissolving with
methanol, carrying out reduction reaction by using
sodium borohydride under the
catalysis of
cerium chloride heptahydrate, and collecting to obtain a second intermediate; taking the second intermediate as a
raw material, dissolving the second intermediate in methylbenzene, and performing
dehydration reaction under the
catalysis of TsOH.H2O to obtain a third intermediate; on the basis of the three intermediates, efficient synthesis of the
gemfibrozil impurity A can be achieved, the synthesis
route is short, and the
process efficiency is high.