To a solution of 0.55 g of 1-methyl-3-nitropyrazole-5-carboxylic acid (prepared as in reported in Example 8) in 10 ml of benzene were added 2 ml of thionyl chloride. The mixture was refluxed for one hour and the solvent evaporated in vacuo to yield a solid residue which was dissolved in 10 ml of dioxane and added in small portions to a solution of 1 g of β-[1-methyl-4-[1-methyl-4-aminopyrrole-2-carboxamido]pyrrole-2-carboxamido]propionamidine, dihydrochloride (prepared as reported in J. Med. Chem. 32,774-778,1989) and 0.2 g of sodium bicarbonate in 10 ml of water. The mixture was stirred for one hour and then brought to pH 4-5 with 10% hydrochloric acid. The Solvent was evaporated in vacuo and the solid residue chromatographed on silica gel eluting whit a mixture methylene chloride-methanol (80:20 by volume), yielding 0.7 g of β-[1-methyl-4-[1-methyl-4-[1-methyl-3-nitropyrazole-5-carboxamido]pyrrole-2-carboxamido]pyrrole-2-carboxamido]propionamidine, hydrochloride.
