To a solution of 5,6-Diamino-4-methyl-2-(1-methyl-piperidin-4-yl)-isoindole-1,3-dione (1.7 g, 5.90 mmol) in MeOH (50 mL) were added AcOH (3 mL) and 4-iodo-2-methoxynicotinaldehyde (1.55 g, 5.90 mmol) and the resulting mixture was heated at 60° C. for overnight. The reaction mixture was evaporated in vacuo and the residue was purified by flash chromatography (5-10% (6% NH3 in MeOH)/CHCl3) to afford 2-(4-Iodo-2-methoxy-pyridin-3-yl)-4-methyl-6-(1-methyl-piperidin-4-yl)-1H-1,3,6-triaza-s-indacene-5,7-dione (1.48 g, 47%) as a yellow solid.
