4-(2-Fluoro-4-iodo-phenylamino)-1-methyl-6-oxo-1,6-dihydro-pyridine-3-carboxylic acid ethyl ester (1.0 g, 2.40 mmol) was reacted with ethynyl-trimethyl-silane (0.70 mL, 4.80 mmol) in the presence of CuI (0.23 g, 1.20 mmol), (Ph3P)2PdCl2 (0.085 g, 0.12 mmol) and TEA (10 mL) in THF/DMF (4:1, 25 mL) which was stirred at room temperature for 24 hours. The reaction mixture was filtered pass through a pad of alumina (neutral). The filtrate was partitioned between water (20 mL) and EtOAc (100 mL). The organic layer was dried and concentrated under reduced pressure. The resulting residue was dissolved in THF (10 mL) and treated with the tetrabutylammonium fluoride (1M in THF, 2.40 mL, 2.4 mmol) which was stirred at room temperature for 15 hours. The reaction was partitioned between water (20 mL), and EtOAc (100 mL). The organic layer was dried over MgSO4, filtered, and concentrated in vacuo. The resulting residue was purified by column chromatography on silica gel (5% MeOH/CH2Cl2 as eluant) to give 4-(4-Ethynyl-2-fluoro-phenylamino)-1-methyl-6-oxo-1,6-dihydro-pyridine-3-carboxylic acid ethyl ester as a light brown solid (0.67 g, 88%). 1H NMR [(CDCl3, 400 MHz] δ9.56 (s, 1H), 8.22 (s, 1H), 7.38 (dd, J=10.1, 1.9 Hz, 1H), 7.25 (s, 2H), 6.01 (s, 1H), 4.38 (q, J=7.1 Hz, 2H), 3.53 (s, 3H), 3.09 (s, 1H), 1.38 (t, J=7.1 Hz, 3H). Anal. Calcd for C17H15FIN2O3: C, 64.96; H, 4.81; N, 8.91. Found: C, 64.89; H, 4.40; N, 8.64.
