TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The base is alkali metal hydroxides, alkali metal carbonates, alkali metal hydride or alkali metal amide (preferably potassium hydroxide, potassium carbonate, sodium hydroxide, sodium carbonate, lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, sodium hydride, sodium amide, lithium amide or potassium hydride). The alkali metal amides and alkali metal hydride of step (d) is sodium amide, sodium hydride, potassium hydride or lithium amide. The reducing agent is sodium borohydride, lithium aluminum hydride or sodium bis(2-methoxyethoxy)aluminum dihydride.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The solvent is acetone, toluene, N, N-dimethyl formamide, dimethyl sulfoxides, or acetonitrile. ACTIVITY - Hypotensive; Respiratory-Gen.    MECHANISM OF ACTION - Endothelial receptor antagonist.    EXAMPLE - Toluene (150.0 ml), potassium carbonate (11.87 g) and 4-tert-butylbenzenesulfonamide (6.72 g) were added at 30 degrees C and stirred for 5 minutes. 4,6-Dichloro-5-(2-methoxyphenoxy)-2,2'-bipyrimidine (10 g) was added at 30 degrees C and the temperature of the reaction mass was raised to reflux. The reaction mass was stirred at reflux for 7 hours. The reaction mass was cooled gradually to room temperature. The reaction mass was stirred for 1 hour. The precipitated solid was filtered, washed with toluene (2 x 10 ml) and dried under vacuum at 55-60 degrees C for 5 hours to obtain 4-tert-butyl-N-(6-chloro-5-(2-methoxyphenoxy)-4-pyrimidinyl)benzenesulfonamide potassium salt (13.16 g). Ethylene glycol (15 ml) and sodium amide (1.13 g) were added at 30 degrees C and stirred for 5 minutes. The temperature of the reaction mass was raised to 50 degrees C and stirred at 50 degrees C for 1 hour. The reaction mass was cooled gradually to room temperature and 4-tert-butyl-N-(6-chloro-5-(2-methoxyphenoxy)-4-pyrimidinyl)benzene sulfonamide (3 g) was added. Ethylene glycol (9 ml) was added to the reaction mass and the temperature of the reaction mass was raised to 70 degrees C. The reaction mass was stirred at 70-75 degrees C for 10 hours. The reaction mass was cooled to room temperature. Water (30 ml) was added to the reaction mass and the resulting mass was stirred for 15 minutes. Concentrated hydrochloric acid (5 ml) was added to the reaction mass and stirred for 3 hours. The precipitated solid was filtered, washed with water (3 x 3 ml) and dried under vacuum at 55-60 degrees C for 10 hours to obtain bosentan (2.34 g, 72%).