To a stirred solution of N,N-dimethylamine hydrochloride (2 g, 24.52 mmol) in dichloromethane (20 mL) was added sequentially N,N-diisopropylethylamine (DIPEA, 12.6 mL, 73.55 mmol) and bromoacetobromide (9.89 g, 19.04 mmol) under an inert atmosphere, maintaining the reaction temperature at 0 °C. The reaction mixture was gradually warmed to room temperature and stirred continuously for 3 hours. The reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was diluted with water (50 mL) and extracted with dichloromethane (2 x 50 mL). The organic phases were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel fast column chromatography with 30% ethyl acetate/hexane as eluent to give N,N-dimethyl-bromoacetamide (1.7 g, 42% yield) as a brown liquid. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 3.86 (s, 2H), 3.10 (s, 3H), 2.99 (s, 3H); LC-MS purity: 71.2%; (M + 2) measured value = 168 (column: XBridge C-18, 50 x 3.0 mm, 3.5 μm; mobile phase: 5 mM NH4OAc ACN; flow rate: 0.8 mL/min).
