The invention relates to a method for preparing an intermediate of
duloxetine hydrochloride. The method comprises the following steps: adding 2-acetylthiophene into concentrated
hydrochloric acid for reacting, preparing a compound of a formula II, adding NaBH4 for reacting, and refining to prepare a compound of a formula III; taking the compound of the formula III and
methyl tertiary butyl ether, adding S-
mandelic acid for reacting, filtering, spraying,
drying to obtain a white granular
solid, dissolving the white granular
solid in water, regulating a pH value, extracting by using
dichloromethane,
drying, and preparing S-(-)-N,N-dimethyl-3-hydroxy-3-(2-thienyl)
propylamine (a compound of a formula I) after
drying. The invention provides a simple method, so that the raw materials are completely dissolved, namely the consumption of NaBH4 is reduced, a reduction reaction can be completely carried out, and the maximum
reaction rate can be 95.6 percent. Meanwhile, the invention provides a method for improving resolution yield and purity, and the maximum yield can be 47.6 percent. According to the improved process, the reaction time is greatly reduced, the operation is simplified, and the total yield of the compound of the formula I which is synthesized in three steps is more than 36 percent.