反应详情

温度

60 °C

To a solution of 6-chloro-7-hydroxychroman-4-carboxylic acid (99 g, 433 mmol) in ethanol (650 mL) was added sulfuric acid (1.2 mL) and the reaction was stirred at 60° C. for 24 hours. The reaction was cooled to ambient temperature and the resulting solids were removed by filtration and discarded. The filtrate was diluted with ethyl acetate (700 mL), washed with water, dried over magnesium sulfate and concentrated. The crude material was purified by silica gel column chromatography eluting with a solvent system of 20% ethyl acetate/hexanes to give ethyl 6-chloro-7-hydroxychroman-4-carboxylate (46 g, 41%).

1. temperatureThe reaction was cooled to ambient temperature
2. customthe resulting solids were removed by filtration
3. additionThe filtrate was diluted with ethyl acetate (700 mL)
4. washwashed with water
5. dry with materialdried over magnesium sulfate
6. concentrationconcentrated
7. customThe crude material was purified by silica gel column chromatography
8. washeluting with a solvent system of 20% ethyl acetate/hexanes