General procedure for the synthesis of methyl 3,4-dimethoxyphenylacetate from methanol and 3,4-dimethoxyphenylacetic acid: 3,4-dimethoxyphenylacetic acid (25.0 g, 127.4 mmol) was dissolved in methanol (100 mL) in a 500 mL round-bottomed flask and a catalytic amount of sulfuric acid (about 10 drops) was added. The reaction mixture was stirred overnight under reflux conditions. After completion of the reaction, it was cooled to room temperature and methanol was removed by distillation under reduced pressure at 40 °C. The crude product was dissolved in dichloromethane (250 mL), washed sequentially with water (5 x 20 mL) and saturated saline (20 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give methyl 3,4-dimethoxyphenylacetate (25.77 g, 96% yield) as an orange oil. Molecular weight: 210.23; yield: 96%; Rf value: 0.25 (cyclohexane:ethyl acetate=3:1). 1H-NMR (CDCl3, δ): 3.56 (s, 2H, CH2), 3.70 (s, 3H, CH3), 3.87 (s, 3H, OCH3), 3.88 (s, 3H, OCH3), 6.82-6.83 (m , 3H, ArH).13C-NMR (CDCl3, δ): 40.6, 51.9, 55.8 (2 × C), 111.2, 112.4, 121.4, 126.4, 148.2, 148.9, 172.2.MS-ESI m/z (% relative abundance): 233.2 ([M+Na]+, 3), 151.1 ( 100).
