The reaction of 4-aminonaphthalene-1,7-disulfonic acid disodium salt (I) with 1-methyl-4-nitropyrrole-2-carbonyl chloride (II) by means of NaOAc in water gives the corresponding nitro-amide (III), which is reduced with H2 over Pd/C in water to the amino-amide (IV). The reaction of (IV) with 4-nitropyrrole-2-carbonyl chloride (V) by means of NaOH and NaOAc yields the nitro-diamide (VI), which is reduced with H2 over Pd/C as before affording the amino-diamide (VII). Finally, this compound is dimerized by reaction with phosgene and KOAc in dioxane/water.