[Br:1][C:2]1[CH:22]=[CH:21][C:5]2[N:6]([CH2:9][C:10]3[CH:20]=[CH:19][C:13]4[N:14]=[C:15]([S:17][CH3:18])[O:16][C:12]=4[CH:11]=3)[CH:7]=[N:8][C:4]=2[CH:3]=1.C1C=C(Cl)C=C(C(OO)=[O:31])C=1>C(Cl)Cl>[Br:1][C:2]1[CH:22]=[CH:21][C:5]2[N:6]([CH2:9][C:10]3[CH:20]=[CH:19][C:13]4[N:14]=[C:15]([S:17]([CH3:18])=[O:31])[O:16][C:12]=4[CH:11]=3)[CH:7]=[N:8][C:4]=2[CH:3]=1A solution of 6-((5-bromo-1H-benzo[d]imidazol-1-yl)methyl)-2-(methylthio)benzo[d]oxazole (327 mg, 0.87 mmol) and m-CPBA (226 mg, 1.31 mmol) in DCM (6 mL) was stirred at 0° C. for 3.5 h. The mixture was washed with aq Na2S2O3 and brine. The organic layer was dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by silica gel chromatography eluting with 1:5 petroleum ether/ethyl acetate to give 6-((5-bromo-1H-benzo[d]imidazol-1-yl)methyl)-2-(methylsulfinyl)benzo[d]oxazole (256 mg, 75.52%) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) δ 8.54 (s, 1H), 7.97 (s, 1H), 7.87-7.89 (m, 2H), 7.57 (d, J=9.0 Hz, 1H), 7.46 (d, J=9.6 Hz, 1H), 7.36 (d, J=6.6 Hz, 1H), 5.68 (s, 2H), 3.18 (s, 3H). LCMS (ESI) m/z 391 (M+H)+.
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