This invention relates to a process for the preparation of N-[2-n butyl-3-{4-[(3- dibutylamino)-propoxy] benzoyl} -1-benzofuran-5-yl]-methane-sulfonamide of formula (I) and its pharmaceutically acceptable salts, according to one of the methylsulfonyl groups of the 2-n- butyl-3-[(di-n-butylamino-3-propoxy)-benzoyl]-5- bis-(methylsulfonamido)-benzofuran of formula (II) is selectively cleaved and if desired the resulting compound of formula (I) is transformed into its salt.
