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温度

0 °C

4-Oxo-4,5,6,7-tetrahydrobenzofuran-3-carboxylic acid was prepared according to a modified literature procedure 1. To a stirring solution of potassium hydroxide (28.06 g, 0.5 mol) in methanol (100 mL) under Nitrogen at 0° C. was added dropwise a solution of cyclohexanedione (56.07 g, 0.5 mol) in methanol (100 mL). The mixture was stirred at 0° C. for 0.5 h, then a solution of ethyl bromopyruvate (66 mL, 0.525 mol) in methanol (100 mL) was added dropwise. After allowing the mixture to stir at ambient temperature for 17 h, a 50% aqueous sodium hydroxide solution (60 mL) was added dropwise and stirring continued an additional 7 h. After dilution with water, the solution was acididfied and the methanol removed in vacuo. Ice water was added and the precipitate filtered and dried in vacuo to afford 4-Oxo-4,5,6,7-tetrahydrobenzofuran-3-carboxylic acid.

1. custom4-Oxo-4,5,6,7-tetrahydrobenzofuran-3-carboxylic acid was prepared
2. stirringto stir at ambient temperature for 17 h
3. stirringstirring
4. waitcontinued an additional 7 h
5. customthe methanol removed in vacuo
6. additionIce water was added
7. filtrationthe precipitate filtered
8. customdried in vacuo