Crude 2-amino-4-(4-amino-phenyl)-thiophene-3-carboxylic acid amide (0.15 mmoles, 1 eq) is dissolved in 5 mL THF and treated with 400 μL of 0.35 M THF solution of 5-indanyl isocyanate (0.15 mmoles, 1 eq). When the reaction is complete, as judged by TLC analysis, the reaction mixture is diluted with 1 mL methanol and 1 mL triethylamine, stirred for 30 minutes, and concentrated to dryness. The residue is purified by prep HPLC yielding pure 2-amino-4-[4-(3-indan-5-yl-ureido)-phenyl]-thiophene-3-carboxylic acid amide.
