Hydrochloric Acid → N-(2-aminoethyl)-N'-(5-amino-1-methyl-1H-pyrazol-4-yl)urea trihydrochloride

To a suspension of tert-butyl {2-[({[1-methyl-5-(tritylamino)-1H-pyrazol-4-yl]amino}carbonyl)amino]ethyl}carbamate (10.8 g) in methanol (50 ml) was added 4M hydrogen chloride solution in dioxane (50 ml). The mixture was stirred at room temperature for 3 hours. The solvent was concentrated in vacuo, and the residue was triturated with ethyl acetate and dried in vacuo to give N-(2-aminoethyl)-N′-(5-amino-1-methyl-1H-pyrazol-4-yl)urea trihydrochloride (5.6 g) as a solid.