[CH3:1][O:2][C:3]([C:5]1[S:6][CH:7]=[C:8]([Br:11])[C:9]=1[OH:10])=[O:4].[C:12](=O)([O-])[O-].[K+].[K+].IC>CC(C)=O>[CH3:1][O:2][C:3]([C:5]1[S:6][CH:7]=[C:8]([Br:11])[C:9]=1[O:10][CH3:12])=[O:4]Methyl-3-hydroxy-4-bromo-2-thiophenecarboxylate (10.0 g, 42.2 mmol) was dissolved in 250 mL of acetone. Potassium carbonate (30.0 g, 217.4 mmol) was added followed by a solution of iodomethane (14.5 mL, 233.0 mmol). The mixture was heated to reflux and continued for 6 h. After cooled to room temperature, the mixture was filtered, the solid material was rinsed with acetone (˜200 mL). The filtrate and rinsing were concentrated under reduced pressure to a solid, further dried on high vacuum, yielding 13.7 g (100%) of methyl-3-methoxy-4-bromo-2-thiophenecarboxylate (MH+=251.0),
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