In a 100 mL round-bottomed flask fitted with a condenser, 4-chloro-6-fluoro-1,7-naphthyridine-3-carbonitrile (0.250 g, 1.20 mmol) and 3-phenoxyaniline (0.245 g, 1.32 mmol) were taken up in 20 mL 2-ethoxyethanol and heated at reflux for 1 hour, until TLC analysis (20% EtOAc in hexanes) showed complete disappearance of the 4-chloronaphthyridine. After cooling to room temperature, the reaction mixture was partitioned between 40 mL each EtOAc and 5% Na2CO3. The aqueous layer was extracted twice more with EtOAc, and the combined organic layers washed three times with brine, dried over anhydrous MgSO4, filtered, and evaporated to give 6-fluoro-4-(3-phenoxyphenylamino)-1,7-naphthyridine-3-carbonitrile as a brown oil of sufficient purity to be used directly in the next step: 1H NMR (400 MHz, DMSO-D6) δ 6.94-7.18 (m, 6 H) 7.33-7.51 (m, 3 H) 8.15 (s, 1 H) 8.68 (s, 1 H) 9.05 (s, 1 H) 10.12 (s, 1 H).
