| abstract |
The invention provides a method for preparing Montelukast sodium, which includes the following steps that sodium alcoholate and Montelukast acid react in an organic solvent; wherein, the Montelukast acid is obtained from acidification of Montelukast cyclohexane. The invention provides a new method for preparing the Montelukast sodium without impurities of cinnamene and lactone; the overall yield of the Montelukast sodium can be on a par with the yields of the methods disclosed by European patent No.737 and No.186. In addition, the invention also provides a method, by which a subsequent coupling reaction can be operated more easily at relatively high reaction temperature, without separating unstable methanesulfonic acid. |