2-(2-Ethoxyphenoxy)ethylamine → Tamsulosin

Beteiligte Stoffe

Reaktionsschritte

2-(o-Ethoxyphenoxy)ethylamine (45 gm) was dissolved in methanol (250 mL). To this 2-methoxy-5-(2-oxopropyl)-benzene sulfonamide (55 gm), catalyst 5% platinum on carbon (12.1 gm) and methanol (330 mL) were added. The mixture was hydrogenated in autocalve at 55° C. at hydrogen pressure of 13 kg/cm2 for 5 hrs. The reaction mixture was cooled and the catalyst was filtered off. To the filtrate containing racemic tamsulosin, oxalic acid (14.3 gm) was added and the solvent was distilled off. To the residue, acetone (700 mL) was added and stirred at reflux temperature for 30 mins. The mixture was cooled, filtered, and the filter cake washed with acetone (50 mL). The salt was further purified by suspending the material in 2-propanol at reflux temperature, cooling to ambient temperature and filtering the solid. The pure oxalate salt of racemic tamsulosin shows a melting range of: 178-182° C. and HPLC purity: 97.24 (area %). The chiral HPLC showed it to be a mixture R and S isomers in the ratio of 50.1 to 49.9. The infrared spectrum of the oxalate salt of racemic tamsulosin as shown in FIG. 1 of the drawing accompanying this specification, exhibited peaks at cm−1: 1154 & 1332 (SO2), 3408 (—NH2), 2983 (NH2+), 1591 (COO—). The 1H-NMR spectrum in CD3SOCD3 gave signals at δ values: 1.06-1.08 (3H, d, >CH—CH3), 1.30-1.33 (3H, t, —CH2—CH3), 3.89 (3H, s, —OCH3), 4.15-4.36 (10 H, 4-CH2, —CH, —NH), 7.61 (2H, s, —NH2), 6.8-7.5 (7H, m, Ar—H).

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