[F:1][C:2]1[CH:3]=[C:4]([CH:10]=[CH:11][C:12]=1F)[C:5]([O:7]CC)=[O:6].[NH:14]1[CH:18]=[N:17][CH:16]=[N:15]1.C([O-])([O-])=O.[K+].[K+].O>CN(C)C=O.C(OCC)(=O)C>[F:1][C:2]1[CH:3]=[C:4]([CH:10]=[CH:11][C:12]=1[N:14]1[CH:18]=[N:17][CH:16]=[N:15]1)[C:5]([OH:7])=[O:6]To a solution of ethyl 3,4-difluoro-benzoate (1.5 g) in N,N-dimethylformamide (15 mL) is added 1,2,4-triazole (1.1 g) and K2CO3 (2.3 g) and the mixture is heated at 150° C. in a microwave oven for 30 min. After cooling to room temperature, water and ethyl acetate are added and the organic layer is dried (MgSO4) and concentrated. The residue is purified by chromatography on silica gel (ethyl acetate/hexane 0:1→1:0). The ester is dissolved in methanol (30 mL) and 4 M aqueous NaOH (3 mL) is added and the mixture is stirred at room temperature for 1 h. The mixture is neutralized with 6 M aqueous HCl, concentrated and then acidified with 6 M aqueous HCl. The precipitate is filtered off washing with a small amount of water and dried by suction to give the title compound.
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