[Br:1][C:2]1[C:6]2=[N:7][C:8]([C:11]([OH:13])=[O:12])=[CH:9][CH:10]=[C:5]2[S:4][CH:3]=1.S1C2C(=NC(C(OC)=O)=CC=2)C=[CH:15]1.BrBr.CCOC(C)=O>C(Cl)(Cl)Cl.C(Cl)(Cl)(Cl)Cl>[Br:1][C:2]1[C:6]2=[N:7][C:8]([C:11]([O:13][CH3:15])=[O:12])=[CH:9][CH:10]=[C:5]2[S:4][CH:3]=1
3-Bromo-thieno[3,2-b]pyridine-5-carboxylic acid (Gronowitz, S.; Westerlund, C.; Hornfeldt, A. -B.; Acta Chem Scand. 29, 233, 1975) was esterified to the corresponding methyl ester. To a solution of the resulting methyl thieno[3,2-b]pyridine-5-carboxylate 9.7 g, 50.2 mmol) in CHCl3 at 0° C. was added a solution of bromine (16 g, 100.4 mmol) in CCl4 (150 mL) dropwise. The mixture was warmed to r.t. and stirred for 72 h. EtOAc (750 mL) was added. The mixture was washed with NaHSO3, dried (anhyd. MgSO4) and concentrated in vacuo. The residue was purified by chromatography on silica gel to give 2.84 g (21%) of the title compound and 5.5 g of starting material.
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