The present invention discloses a new process for the synthesis of tamsulosin and its aralkylamine derivatives, especially (R)-(-)-5-{2-[2-(2-alkoxyphenoxy) ethylamino]propyl}-2-alkoxybenzenesulfonamides having the following formula 1 (where R.sup.1 and R.sup.2 represent C.sub.1-C.sub.4 alkyl groups) and their hydrochloride thereof, and other various pharmaceutical used salts. ##STR00001## Tamsulosin hydrochloride (R.sup.1=Et, R.sup.2=Me, in its hydrochloride salt form) is an antagonist of .alpha.-A adrenoceptors in the prostate. Tamsulosin.cndot.HCl occurs as white crystals, which melt with decomposition at approximately 230.degree. C. It is sparingly soluble in water and in methanol, slightly soluble in glacial acetic acid and in ethanol, and practically insoluble in ether.