[OH-].[Na+].[I:3][C:4]1[C:9]2[C:10](=[O:15])[O:11][C:12](=O)[NH:13][C:8]=2[CH:7]=[CH:6][CH:5]=1>CO.[OH-].[Na+]>[NH2:13][C:8]1[CH:7]=[CH:6][CH:5]=[C:4]([I:3])[C:9]=1[C:10]([O:11][CH3:12])=[O:15]To a stirred solution of sodium hydroxide (0.35 g, 8.8 mM) in methanol (31 mL) was added 5-iodo-2H-3,1-benzoxazine-2,4(1H)-dione (18.5 g, 64.0 mM). The mixture was heated at 60° C. for 1.5 hr. An additional quantitiy of sodium hydroxide (0.10 g, 2.5 mM) was added to the reaction mixture and stirring at 60° C. was continued for an additonal 1 hr. After cooling to room temperature, the reaction mixture was concentrated and the residue was taken up in ethyl acetate. The ethyl acetate was washed successively with water, brine, dilute aqueous sodium hydroxide, and water. After drying over MgSO4, the ethyl acetate was filtered and concentrated to leave (13.9 g, 78.4%) of the title ester as a brown oil; MS(CI): 278 (M+H).
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