This invention discloses a method for preparing
raloxifene EP
impurity B, comprising the following steps: dissolving 6-methoxy-2-(4-methoxyphenyl)
benzothiophene (Ⅰ) as a
raw material in
solvent one, adding NIS, and then adding a free
radical initiator to react and obtain intermediate III; dissolving 4-[2-(1-pyrrolidinyl)ethoxy]benzoate salt (II) in
solvent two, adding
solvent two or not, and then adding a chlorinating agent to react and generate intermediate IV; dissolving intermediate III in solvent three, adding a Lewis acid, and then adding intermediate IV, and performing a Friedel-Crafts
acylation reaction to generate intermediate V; dissolving intermediate V in solvent four, adding a
demethylating agent, and generating
bisphenol hydroxyl intermediate VI under
demethylation conditions; dissolving intermediate VI in solvent five, adding a
reducing agent, and generating intermediate VII through a reduction reaction; dissolving intermediate VII in
formic acid, stirring, evaporating, and finally lyophilizing to generate the
formate target product VIII.