Synthesis
Example 5: Preparation of 6-methoxy-3-benzofuranone
1. Slowly add chloroacetonitrile (3.5 mL, 55.2 mmol) dropwise to a stirred solution of anhydrous dioxane (30 mL) containing 3-methoxyphenol (5 mL, 46 mmol) and zinc chloride (6.9 g, 50.6 mmol) at room temperature.
2. Saturate the reaction solution with dry hydrogen chloride gas.
3. After stirring the reaction mixture overnight at room temperature, the yellow precipitate was collected by filtration and washed with anhydrous ether (100 mL).
4. dissolve the resulting precipitate in water (80 mL) and heat to reflux for 1 hour.
5. Cool the solution to about 40 °C and add 20% w/v aqueous sodium hydroxide (7.5 mL).
6. After stirring at 40 °C for 30 min, formation of a light yellow precipitate was observed.
7. The pH of the reaction system was adjusted to about 7 by dropwise addition of 1 M hydrochloric acid to allow complete precipitation of the precipitate.
8. The precipitate was filtered, washed with water and finally recrystallized by acetone to afford the target compound 6-methoxy-3-benzofuranone as a light yellow powder (4.14 g, 54.8% yield).
1H NMR (ppm): 3.85 (s, OMe); 4.90 (s, CH2); 6.50-6.46 (m, 2H, phenyl); 7.70-7.66 (m, 1H, phenyl).
