Br.Br[C:3]1[S:7][C:6]([NH2:8])=[N:5][CH:4]=1.[CH2:9]([O:11][C:12](=[O:21])[C:13]1[CH:18]=[CH:17][C:16]([OH:19])=[C:15]([F:20])[CH:14]=1)[CH3:10].C(=O)([O-])[O-].[Cs+].[Cs+]>CC(C)=O>[CH2:9]([O:11][C:12](=[O:21])[C:13]1[CH:18]=[CH:17][C:16]([O:19][C:3]2[S:7][C:6]([NH2:8])=[N:5][CH:4]=2)=[C:15]([F:20])[CH:14]=1)[CH3:10]To a solution of 5-Bromothiazole-2-amine hydrobromide (1.55 g, 5.97 mmol) in acetone (100 mL) was added 3-fluoro-4-hydroxy benzoic acid ethyl ester (1.1 g, 5.97 mmol) and cesium carbonate (3.89 g, 11.94 mmol) under argon atmosphere and refluxed for 5 hrs. The reaction mixture was cooled to room temperature and filtered; the filtrate was concentrated under reduced pressure. The residue was partitioned in between ethyl acetate and water. The layers were separated, the organic layer was washed with cold 2 N NaOH (10 mL), brine and dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to provide 4-(2-amino-thiazol-5-yloxy)-3-fluoro-benzoic acid ethyl ester (0.68 gm).
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