TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The reaction is performed in homogeneous conditions. The coupling reaction is carried out in the presence of a ligand. Preferred Components: The palladium catalyst is palladium(II) acetate, tris(dibenzylideneacetone)dipalladium(0) (both preferred), tetrakis(triphenylphosphine) palladium, dichlorobis(triphenylphosphine)palladium (II), (1,1-bis(diphenylphosphino)ferrocene) dichloropalladium(II), bis(acetonitrile)dichloropalladium (II), and bis(tri-tert-butylphosphine)palladium(0). The ligand is of the phosphine type, preferably triphenylphosphine or tri-tert-butylphosphine. The solvent medium is water and/or an organic solvent. The organic solvent is tetrahydrofuran, 1,2-dimethoxyethane (DME), N,N-dimethylformamide (DMF), diethoxymethane (DEM), toluene, xylene, methanol, ethanol, propanol, dioxane, acetonitrile or dimethylacetamide (DMA). The solvent medium further comprises an organic base including tertiary amines, like triethylamine (TEA) or N,N-diisopropylethylamine (DIPEA), or acetates; or other ammonia compounds in which one or more hydrogen have been substituted by alkyl or aryl radicals such as ethyl, isopropyl, benzyl, phenyl or pyridine. Preferred Definitions:    R = butyl; and    R1 = triflate.    ACTIVITY - Hypotensive; Respiratory-Gen.; Cardiovascular-Gen.; Vasotropic; Cerebroprotective; Antianginal.    MECHANISM OF ACTION - Endothelin receptor antagonist.    EXAMPLE - N-(6-(2-tert-Butoxy-ethoxy)-5-(6-methoxy-cyclohexa-2,3,5-trienyloxy)-(2,2')bipyrimidinyl-4-yl)-4-tert-butyl-benzenesulfonamide (1.0 g, 1.64 mmole) in 98% formic acid (3 ml) was heated at 85 degrees C and the reaction mixture stirred for 90 minutes. The reaction was then cooled at room temperature and was added over dichloromethane/water. The bottom layer was cut and then back-extracted twice with dichloromethane. The combined organic extracts were dried and evaporated. The residue was dissolved in 10 ml of methanol and then solid potassium carbonate (715 mg, 5.2 mmole) was charged. The reaction mixture was aged at that temperature for 1 hour. Then, ethyl acetate and water were added, the pH was adjusted to 3-3.5 with 3M hydrochloric acid and the organic layer was separated and dried. After solvent was evaporated, the residue thus obtained was purified by column chromatography over silica gel affording 4-tert-butyl-N-(6-(2-hydroxyethoxy)-5-(2-methoxy-phenoxy)-(2,2')bipyrimidinyl-4-yl)-benzenesulfonamide (780 mg, 86 % yield) as a yellowish solid. The crude bosentan was further purified by recrystallization in hot water/ethanol affording pure bosentan monohydrate as a white solid (655 mg, 70 %).