[CH3:1][O:2][C:3]([C:5]1[S:6][CH:7]=[CH:8][C:9]=1[OH:10])=[O:4].[C:11]([O-])([O-])=O.[K+].[K+].CI>CC(C)=O>[CH3:11][O:10][C:9]1[CH:8]=[CH:7][S:6][C:5]=1[C:3]([O:2][CH3:1])=[O:4]To a mixture of 3-hydroxy-thiophene-2-carboxylic acid methyl ester (5 g, 31.6 mmol) and K2CO3 (22.2 g, 161 mmol) in acetone (50 mL) is added CH3I (10.8 mL, 173 mmol,) dropwise at 0° C. The reaction mixture is heated at 55° C. for 4 hours, cooled to room temperature, filtered through diatomaceous earth, and the filtrate is concentrated under vacuum. The residue is diluted with water (100 mL) and extracted with ethyl acetate (2×200 mL). The combined organic layer is washed with brine solution (50 mL), dried over Na2SO4, and evaporated under vacuum to give title compound as a brown solid (5.9 g). ESI/MS m/z 173.1 (M+H)+.
Loading…