反应详情

3.75 g of 3-carboxy-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-one was suspended in 75 ml of N,N-dimethylformamide. Thereto was dropwise added 4.6 g of phosphorus oxychloride at -10° to -5° C. The mixture was stirred for 3 hours at the same temperature. The reaction mixture was dropwise added to 40 ml of a concentrated aqueous ammonia solution at 10°-20° C. The mixture was stirred for 30 minutes at the same temperature and then adjusted to pH 4 with 4N hydrochloric acid. The resulting crystal was collected by filtration, washed with water and recrystallized from acetic acid to obtain 2.81 g (yield: 75.1%) of 3-carbamoyl-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-one having a melting point of >250° C.

1. customat -10° to -5° C
2. stirringThe mixture was stirred for 30 minutes at the same temperature
3. filtrationThe resulting crystal was collected by filtration
4. washwashed with water
5. customrecrystallized from acetic acid