Formic Acid → Iguratimod

Participants

Reaction Steps

27.6 g of formic acid was added to 30.6 g of acetic anhydride. The mixture was stirred for 1.5 hours at 40°-45° C. The reaction mixture was dropwise added to a solution of 34.6 g of 3-amino-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-one dissolved in 400 ml of methylene chloride. The mixture was stirred for 1 hour at 20°-25° C. 400 ml of diisopropyl ether was added thereto. The resulting crystal was collected by filtration and recrystallized from acetonitrile to obtain 27.3 g (yield: 73%) of 3-formylamino-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-one having a melting point of 236°-238° C.

Provenance & Evidence