Under argon protection, 3,N-dimethoxy-N-methylbenzamide (5.86 g, 30.0 mmol) was dissolved in THF (150 mL) and cooled to 0°C. Slowly add ethylmagnesium bromide (0.960 mol/L THF solution, 100 mL, 96.0 mmol). After addition, bring to room temperature and stir for 3.5 hours. Upon completion of the reaction, the reaction was quenched with 1 mol/L hydrochloric acid and subsequently extracted with ethyl acetate. The organic layers were combined, washed sequentially with water and saturated saline, and dried over anhydrous sodium sulfate. Concentration under reduced pressure afforded m-methoxypropiophenone (4.93 g, 30.0 mmol, quantitative yield) as a yellow oil.1H-NMR (400 MHz, CDCl3): δ 1.23 (3H, t, J = 7.3 Hz), 3.00 (2H, q, J = 7.3 Hz), 3.86 (3H, s), 7.10 (1H, dd, J = 7.9 , 2.4 Hz), 7.37 (1H, t, J = 7.9 Hz), 7.50 (1H, t, J = 2.4 Hz), 7.54 (1H, d, J = 7.9 Hz).
