General procedure for the synthesis of 2-bromo-1-(3,4-dimethoxyphenyl)ethanone from 3,4-dimethoxyacetophenone: Benzyltrimethylammonium tribromide (2.16 g, 5.55 mmol) was added to a stirred mixture of 1-(3,4-dimethoxyphenyl)ethanone (1.0 g, 5.55 mmol) in a mixed solution of dichloromethane (6 mL) and methanol (3 mL). The reaction mixture was stirred at room temperature for 16 hours before dilution with dichloromethane (80 mL) and water (40 mL) to separate the organic layer. The aqueous phase was extracted twice with dichloromethane (80 mL x 2). All organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford 2-bromo-1-(3,4-dimethoxyphenyl)ethanone (1.20 g, 4.63 mmol, 83% yield) as a brown solid. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 7.63 (s, 1H), 7.57 (d, J=2.1Hz, 1H), 6.94 (d, J=8.4Hz, 1H), 4.43 (s, 2H), 3.98 (s, 6H).
