反应详情

80 ml of dioxane and 40 ml of 6N hydrochloric acid were added to 4.03 g of 3-ethoxycarbonyl-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-one. The mixture was refluxed for 30 minutes. The reaction mixture was cooled. 200 ml of water was added thereto. The resulting crystal was collected by filtration, washed with water and recrystallized from acetic acid to obtain 3.41 g (yield: 91%) of 3-carboxy-7-methylsulfonylamino-6-phenoxy4H-1-benzopyran-4-one having a melting point of >250° C.

1. temperatureThe mixture was refluxed for 30 minutes
2. temperatureThe reaction mixture was cooled
3. filtrationThe resulting crystal was collected by filtration
4. washwashed with water
5. customrecrystallized from acetic acid