A solution of 1.2 g (5.3 mmol) of 5-bromo-2,4-dichloro-pyrimidine in 30 ml of acetonitrile is added to a solution of 1.5 g (5.2 mmol) of N-(5-amino-pentyl)-3-nitro-benzenesulfonamide in 50 ml of acetonitrile. The reaction mixture is mixed with 1.0 ml (7.2 mmol) of triethylamine and stirred for 17 hours at room temperature. After water (50 ml) is added, it is extracted (2×) with ethyl acetate. The combined organic phases are dried (Na2SO4), filtered and concentrated by evaporation. The remaining residue is purified by chromatography (hexane/ethyl acetate 2:1, Flashmaster II). 1.5 g (3.1 mmol, corresponding to 60% of theory) of the product is obtained.
