[CH3:1][O:2][C:3](=[O:20])[C:4]1[CH:9]=[C:8]([NH2:10])[C:7]([NH2:11])=[C:6]([F:12])[C:5]=1[NH:13][C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1.Cl.[CH3:22][C:23](=O)CC(=O)C.C([O-])(O)=O.[Na+]>C(O)C>[CH3:1][O:2][C:3]([C:4]1[C:5]([NH:13][C:14]2[CH:15]=[CH:16][CH:17]=[CH:18][CH:19]=2)=[C:6]([F:12])[C:7]2[N:11]=[C:22]([CH3:23])[NH:10][C:8]=2[CH:9]=1)=[O:20]4,5-Diamino-3-fluoro-2-phenylamino-benzoic acid methyl ester 6c (0.20 g, 0.73 mmol) is suspended in ethanol (3 mL) and 5 M aqueous HCl (1 mL., 5.00 mmol) is added. The reaction mixture is brought to reflux under N2 and then 2,4-pentanedione (0.150 mL, 1.45 mmol) is added. The reaction mixture is stirred at reflux for 60 minutes. The reaction mixture is cooled to room temperature and treated with saturated aqueous NaHCO3 until the pH of the reaction mixture is pH 7 and is then concentrated under reduced pressure to dryness. The residue is diluted with ethyl acetate and water, poured into a separatory funnel and the layers separated. The ethyl acetate layer is washed with brine, dried (Na2SO4) and concentrated under reduced pressure. The red solid residue is triturated with diethyl ether to yield a light brown solid and a red filtrate. The solid is collected and washed with diethyl ether to yield 0.20 g (91%) of the pure desired product as a light brown solid. MS ESI (+) m/z 300 (M+1) detected.
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