Step 6-J: Methylmagnesium bromide (44 mL, 61.6 mmol, 1.4 M in tetrahydrofuran) was slowly added dropwise to tetrahydrofuran (50 mL) at -78 °C. Subsequently, a solution consisting of 4-bromo-2-chloro-N-methoxy-N-methylbenzamide (3.52 g, 12.7 mmol, from Step 6-I) dissolved in tetrahydrofuran (30 mL) was added. The reaction mixture was stirred at -78°C for 45 minutes, then brought to room temperature and continued stirring for 1.5 hours. After completion of the reaction, the mixture was extracted with ethyl acetate (3 times), the organic phases were combined, washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated in vacuum. The crude product was purified by recrystallization (solvent: ethyl acetate/hexane) to afford 1-(4-bromo-2-chlorophenyl)ethanone as a white solid (1.1 g, 37% yield).
