Synthetic method for (S)-(-)-3-methylamino-1-(2-thienyl)-1-propanol

The present invention relates to a method for preparing (S)-(-)-3-methylamino-1-(2-thienyl)-1-propanol with high purity. The method comprises: taking the (S)-(-)-3-dimethylamino-1-(2-thienyl)-1-propanol as an starting material; in the presence of an organic solvent, protecting hydroxyl by a hydroxy protecting agent, then carrying out a demethylation reaction; and finally, carrying out a hydroxyl de-protection reaction in a strong alkaline environment in the presence of a hydroxyl de-protection agent, thereby obtaining a target product. According to the synthetic method, the (S)-(-)-3-methylamino-1-(2-thienyl)-1-propanol is over 99% in purity and ee value, and is over 80% in the yield, and the method is suitable for industrial production.