Method for preparing silodosin chiral intermediate

The present invention provides a method for synthesizing a silodosin intermediate with a high enantiomeric purity. The method comprises the steps of using 1-[3-(benzyloxy)propyl]-5-bromoindoline as the raw material, performing a bromine lithium exchange reaction with an organolithium reagent to obtain 1-[3-(benzyloxy)propyl]-5-lithiumindoline, performing a Weinreb amidization reaction with (R)-N-(alkoxycarbonyl)alanine to obtain the silodosin intermediate with a good yield and enantioselectivity. The method has the advantages of simple operation, cheap and easily-available raw materials, highenantiomeric purity of the product and no resolution step, and has extremely high application value for industrial preparation of silodosin. 本发明提供种合成高对映纯度的西洛多辛中间体的方法。该方法以1-[3-(苄氧基)丙基]-5-溴-吲哚啉为原料，与有机锂试剂进行溴锂交换反应，得到1-[3-(苄氧基)丙基]-5-锂-吲哚啉，再与(R)-N-烷氧羰基-丙氨酸Weinreb酰胺反应，以良好的产率和对映选择性得到西洛多辛中间体。该方法操作简单，原料廉价易得，产物对映纯度高，无需拆分步骤，对于西洛多辛的工业制备具有很高的应用价值。