[F:1][C:2]1[C:7]2[N:8]=[CH:9][O:10][C:6]=2[CH:5]=[C:4]([C:11]([OH:13])=[O:12])[C:3]=1[NH:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][C:16]=1[F:21].C1C(=O)N([I:29])C(=O)C1.FC(F)(F)C(O)=O>CN(C=O)C>[F:1][C:2]1[C:7]2[N:8]=[CH:9][O:10][C:6]=2[CH:5]=[C:4]([C:11]([OH:13])=[O:12])[C:3]=1[NH:14][C:15]1[CH:20]=[CH:19][C:18]([I:29])=[CH:17][C:16]=1[F:21]To a solution of 4-fluoro-5-((2-fluorophenyl)amino)benzo[d]oxazole-6-carboxylic acid (7.22 g, 24.88 mmol) in DMF (50 mL) was added NIS (6.08 g, 26.37 mmol) followed by trifluoroacetic acid (1.0 mL). After stirring for 5 h at ambient temperature, the reaction was quenched by saturated NH4Cl (aq.). The solution was extracted with ethyl acetate (150 mL×3). The combined organic extracts were washed with water (100 mL) and brine (100 mL) successively, dried over Na2SO4 and concentrated in vacuo. The crude product was purified by column chromatography on silica gel (CH2Cl2/MeOH, 50:1, v/v) and gave the desired product (brown solid, 6.34 g, 61.2% yield). 1H NMR (400 MHz, DMSO-d6): δ 8.97 (s, 1H), 8.58 (s, 1H), 8.18 (s, 1H), 7.58 (dd, J=11.0, 1.7 Hz, 1H), 7.34 (d, J=8.5 Hz, 1H), 6.55 (m, 1H).
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