A PROCESS FOR THE PREPARATION OF R (-) TAMSULOSIN HYDROCHLORIDE

摘要

The invention discloses a process for the preparation of highly pure R (-)-5-(2-(2-(2-ethoxy phenoxy) ethylamine) propyl)-2-methoxy benzene sulfonamide hydrochloride used to treat symptoms of urinary difficulty. R-(-)-2-(4-methoxy phenyl)- 1 -methyl ethyl amine is condensed with halo-acetyl halide in the presence of base and a halogenated solvent. The resulting R-(-)- halo-N-[2-(4-methoxy phenyl)- 1 -methyl ethyl] acetamide is treated with chlorosulphonic acid and ammonia. R-(-)-N-[2-(3-amino sulfonyl-4-methoxy phenyl)- 1 -methyl ethyl]-2- haloacetamide obtained is treated with 2- ethoxy phenol in the presence of an inorganic base and water to obtain R-(-)-N-[2-(3-amino sulfonyl-4-methoxy phenyl)- 1 -methyl ethyl]-2-(2- ethoxy phenoxy) acetamide in high yield and purity. The amide obtained is reduced to obtain the Tamsulosin base, which is then purified and converted to its hydrochloride salt.