Example 6 Preparation of 2-bromo-1-o-tolylacetophenone (I15): 2-methylbenzoyl chloride (169 μL, 1.29 mmol) was dissolved in anhydrous acetonitrile (5 mL) under nitrogen protection and cooled to 0°C. Subsequently, (diazomethyl)-trimethylsilane (1.94 mL, 3.88 mmol, 2 M hexane solution) was slowly added. The reaction mixture was stirred at room temperature for 15 h. The reaction mixture was again cooled to 0 °C and 48% hydrobromic acid (512 μL, 4.53 mmol) was slowly added. The reaction mixture was continued to be stirred at room temperature for 3 hours. After completion of the reaction, the organic layer was separated by adding ethyl acetate (EtOAc) and water for extraction. The aqueous phase was neutralized with 1 M sodium hydroxide (NaOH) and extracted again with ethyl acetate. The organic layers were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure to afford 2-bromo-1-o-toluene ethanone (250 mg, 91% yield). The intermediate could be used for subsequent reactions without further purification.1H NMR (300 MHz, DMSO-d6) δ ppm: 7.82-7.91 (m, 1H), 7.45-7.52 (m, 1H), 7.25-7.40 (m, 2H), 4.86 (s, 2H), 2.41 (s, 3H).
