General procedure for the synthesis of 4-fluoro-3-nitroacetophenone from 4-fluoroacetophenone: 1-(4-fluorophenyl)ethanone (1.10 g, 7.97 mmol) was dissolved in concentrated H2SO4 (5 mL) under stirring conditions. Subsequently, a mixed acid consisting of concentrated HCl and concentrated H2SO4 (2 mL) was slowly added. HNO3 (1.50 mL) was added slowly and dropwise at -15°C. The reaction mixture was continued to be stirred at -15 °C for 80 min, after which it was poured into ice-cold H2O (120 mL) and extracted with EtOAc (2 × 100 mL). The organic layers were combined and washed sequentially with H2O (100 mL) and brine (100 mL), and the organic layer was separated, dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude product was purified by column chromatography (silica gel, 100-200 mesh, 40% EtOAc in hexane solution) to afford 4-fluoro-3-nitroacetophenone (0.80 g, 55%) as an off-white solid.1H NMR (400 MHz, CDCl3) δ 2.64 (s, 3H), 7.39 (t, J=9.30 Hz, 1H), 8.20- 8.26 (m, 1H), 8.57-8.66 (m, 1H).
