Maleic Anhydride → 4-[(5-bromo-1H-indazol-3-yl)amino]-4-oxo-2-butenoic acid

Participants

Reaction Conditions

Reaction Steps

350 mg of maleic anhydride are added to 500 mg of 5-bromo-1H-indazole-3-amine, prepared as described in U.S. Pat. No. 3,133,081, in 20 cm3 of toluene. The medium is refluxed at about 110° C. for one hour. The heating is then stopped and the mixture is stirred at about 19° C. for 12 hours. The precipitate formed is filtered off on a sinter funnel and rinsed with 20 cm3 of diisopropyl ether, 2 cm3 of ethyl acetate and 2 cm3 of dichloromethane. After drying (90 Pa; 45° C.), 448 mg of 4-[(5-bromo-1H-indazol-3-yl)amino]-4-oxo-2-butenoic acid, Z form, are obtained in the form of a yellow solid melting at 172° C.

Provenance & Evidence