To a stirred solution of 1-bromo-2-fluorobenzene (10 g, 57 mmol) in tetrahydrofuran (100 mL) was slowly added n-butyllithium (25 mL, 62.9 mmol, 2.5 M hexane solution) under nitrogen protection and at -70 °C. After maintaining the reaction at -70°C for 20 minutes, the solution was slowly added dropwise to a solution of diethyl oxalate (39 mL, 285 mmol) in tetrahydrofuran (100 mL). After the dropwise addition was completed, the reaction mixture was gradually warmed to room temperature. After continued stirring for 1 hour at room temperature, the reaction mixture was poured into water (150 mL) and extracted with ethyl acetate (2 x 100 mL). The organic phases were combined and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (240 g) with ethyl acetate/hexane (1:49) as eluent to afford the target compound ethyl 2-(2-fluorophenyl)-2-oxoacetate as a colorless oil (5.6 g, 50% yield). The product was confirmed by 1H NMR (CDCl3): δ 7.95 (m, 1H), 7.62 (m, 1H), 7.35-7.13 (m, 2H), 4.44 (q, J=7.1Hz, 2H), 1.40 (t, J=7.1Hz, 3H). The mass spectrum (ES+) showed the molecular ion peak m/z = 197 (M+H)+.
