[NH2:1][C:2]1[CH:11]=[C:10]([F:12])[C:9]([S:13](=[O:16])(=[O:15])[NH2:14])=[CH:8][C:3]=1[C:4](OC)=[O:5].C(OCC)(=O)C.[OH-].[NH4+:24]>>[NH2:1][C:2]1[CH:11]=[C:10]([F:12])[C:9]([S:13](=[O:16])(=[O:15])[NH2:14])=[CH:8][C:3]=1[C:4]([NH2:24])=[O:5]A mixture of 4.8 g (0.0193 molecule) of methyl 2-amino-4-fluoro-5-sulphamylbenzoate (7) in 75 ml of concentrated ammonium hydroxide was taken to 50°, to obtain complete solution. The solution was cooled and returned to ambient temperature, diluted with a fresh solution of 75 ml of concentrated ammonium hydroxide and allowed to rest for 65 hours. It was extracted with ethyl acetate (1×250 ml; 4×500 ml) and the extracts were combined, dried over anhydrous magnesium sulphate and concentrated in vacuo, to give a solid. The latter was ground with 25 ml of ethyl acetate, to give 2.7 g (60.0%) of pure product (8).
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