[Br:1][C:2]1[CH:3]=[C:4]2[N:10]=[C:9]([NH:11]C(=O)C3C=CC=CC=3)[S:8][C:5]2=[N:6][CH:7]=1.[OH-].[Na+]>OS(O)(=O)=O>[Br:1][C:2]1[CH:3]=[C:4]2[N:10]=[C:9]([NH2:11])[S:8][C:5]2=[N:6][CH:7]=1A solution of N-(6-bromothiazolo[5,4-b]pyridin-2-yl)benzamide III (2.0 g, 5.98 mmol) in 70% H2SO4 (10.0 mL) was heated to 140° C. for 1 h. After the completion of the reaction (TLC monitoring), the reaction mixture was poured onto crushed ice, basified with 30% aqueous NaOH solution till pH 8.0 and extracted with EtOAc (3×150 mL). The combined organics was washed with brine, dried (Na2SO4), filtered and concentrated under reduced pressure to obtain the desired product (1.34 g, 98%). 1H NMR (400 MHz, DMSO-d6): δ 7.85 (d, J=2.0 Hz, 1H), 8.05 (br s, 2H) and 8.18 (d, J=2.0 Hz, 1H).
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