918867-88-6

The invention includes an improved process for producing tamsulosin comprising reacting 5-(2-aminopropyl)-2-methoxybenzenesulfonamide with 2-(o-ethoxyphenoxy)ethyl bromide in an organic phosphite solvent to obtain tamsulosin. Optically pure (R)- 5-(2-aminopropyl)-2- methoxybenzenesulfonamide can be employed to produce optically pure (R)-tamsulosin product. The organic phosphite solvent utilized in the reaction can include tri-alkyl phosphites such as triethyl phosphite, trimethyl phosphite, and tributyl phosphite. Additionally, processes for producing tamsulosin having a low concentration of by-product contaminants, such as 5-((R)-2- {Bis-[2-(2-ethoxyphenoxy)ethyl]amino}-propyl)-2-methoxybenzenesulfonamide, and the use of such by-products to monitor the chemical purity of tamsulosin, are provided.

In the present invention, the process for the preparation of tamsulosin hydrochloride and subsequent purification with thermal crystallisation to provide essentially pure tamsulosin hydrochloride is disclosed.