A solution of 6-chloro-8-((4-methoxybenzyl)(5-methylpyridin-2-yl)amino)imidazo[1,2-b]pyridazine-3-carboxylic acid (0.07 g, 0.165 mmol), 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride (0.047 g, 0.248 mmol), 1-hydroxybenzotriazole (0.033 g, 0.248 mmol), TEA (0.069 mL, 0.495 mmol) and pyridin-4-amine (0.023 g, 0.248 mmol) in acetonitrile (2 mL) was heated to 80° C. for 16 hours. The solution was quenched with EA/water. The organic layer was washed with sat NaHCO3 and sat NaCl. The organic layer was dried with Na2SO4, filtered and concentrated in vacuo to give the crude product mixture. The crude product was purified by ISCO (5% EtOAC/DCM; 12 g column), followed by ISCO (5% MeOH/DCM; 12 g column) to afford the title compound (32 mg). [M+H]=500.
