[CH3:1][O:2][C:3]1[CH:4]=[C:5]([CH:10]=[C:11]([OH:14])[C:12]=1[OH:13])[C:6]([O:8][CH3:9])=[O:7].C(=O)([O-])[O-].[K+].[K+].Br[CH:22](Br)[CH3:23].Cl>CC(C)=O.O>[CH3:1][O:2][C:3]1[CH:4]=[C:5]([CH:10]=[C:11]2[O:14][CH2:23][CH2:22][O:13][C:12]=12)[C:6]([O:8][CH3:9])=[O:7]Combine methyl 3-methoxy-4,5-dihydroxybenzoate (0.5 g, 2.5 mmol) and potassium carbonate (1.74 g, 12.65 mmol) in acetone (25 mL). Add dibromoethane (2.37 g, 12.65 mmol). Heat to reflux. After 24 hours, cool in an ice bath, acidify with a 1 M aqueous hydrochloric acid solution (35 mL), add water (25 mL), and extract three times with ethyl acetate. Combine the organic layers and extract with brine. Dry over MgSO4, filter, and concentrate in vacuo to give methyl 3-methoxy-4,5-ethylenedioxybenzoate.
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