To a suspension of 4-(2-fluoro-4-iodophenylamino)-1,5-dimethyl-6-oxo-1,6-dihydropyridazine-3-carboxylic acid (41 mg, 0.10 mmol) and HOBt (28 mg, 0.21 mmol) in DMF (1.5 mL) was added EDCI (40 mg, 0.21 mmol) at room temperature. The resulting mixture was stirred for 1.5 hours. O-(2-Vinyloxy-ethyl)-hydroxylamine (21 mg, 0.20 mmol) and TEA (0.030 mL, 0.22 mmol) was added to the activated ester at room temperature. After stirring for 1.5 hours, the reaction mixture was diluted with EtOAc and washed with saturated aqueous NH4Cl, brine, saturated aqueous NaHCO3 (2×), and brine. The organic layer was separated, dried over MgSO4, filtered, and concentrated under reduced pressure to give 4-(2-fluoro-4-iodophenylamino)-1,5-dimethyl-6-oxo-N-(2-(vinyloxy)ethoxy)-1,6-dihydropyridazine-3-carboxamide that was used directly without further purification. The title compound was prepared by the procedure previously described in Example 1 (step J) using the crude 4-(2-fluoro-4-iodophenylamino)-1,5-dimethyl-6-oxo-N-(2-(vinyloxy)ethoxy)-1,6-dihydropyridazine-3-carboxamide (40% yield over two steps). MS APCI (−) m/z 461 (M−1) detected; 1H NMR (400 MHz, CD3OD) δ 7.52 (dd, 1H), 7.44 (d, 1H), 6.63 (t, 1H), 3.98 (t, 2H), 3.80 (s, 3H), 3.74 (t, 2H), 1.78 (s, 3H).
