[C:1]([C:5]1[S:9][C:8]2[CH:10]=[C:11]([F:14])[CH:12]=[CH:13][C:7]=2[C:6]=1[NH2:15])([O:3]C)=[O:2].[OH-].[Na+].C(O)(C)C>O>[NH2:15][C:6]1[C:7]2[CH:13]=[CH:12][C:11]([F:14])=[CH:10][C:8]=2[S:9][C:5]=1[C:1]([OH:3])=[O:2]At 50° C., add to a stirring solution of 2-carbomethoxy-3-amino-6-fluoro-benzo[b]thiophene (prepared according to U.S. Pat. No. 5,143,923), (90.1 g, 0.4 mol) in H2O (450 mL), a 50% aqueous solution of NaOH (64 g, 0.8 mol) over 2-3 min. Heat the reaction to 70-73° C. and continue to stir for 3 h. Add 10% aqueous isopropanol (45 mL) and bring to reflux. Remove the isopropanol under N2 and add H2O (300 mL). Cool the reaction mixture to between 7-10° C. and add concentrated HCl (80 mL). Add H2O (650 mL), cool to 5-70° C., filter the resulting solid, and wash the filter cake with H2O (2×150 mL). Dry the solid under vacuum at 35° C. to obtain 80.6 g (94.7%) of solid mp 160-163° C., TLC on silica gel (dichloromethane/methanol, 3:1), Rf=0.69.
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