m-Chloroperbenzoic acid → 6-((5,6-dimethoxy-1H-benzo[d]imidazol-1-yl)methyl)-2-(methylsulfinyl)benzo[d]oxazole

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Reaction Steps

To a stirred solution of 6-((5,6-dimethoxy-1H-benzo[c]imidazol-1-yl)methyl)-2-(methylthio)benzo[d]oxazole (270 mg, 0.761 mmol) from Step 2 of Example 34 in DCM (5 mL) at 0° C. was added 70% meta-chloroperbenzoic acid (262 mg, 1.14 mmol), and the mixture was allowed to warm to rt and stirred for a further 4.5 h. To the mixture was added saturated aq NaHCO3 and the organic layer was separated. The aqueous layer was extracted with DCM and the combined organic layers were washed with saturated aq NaHCO3. The organic layer was separated, dried over MgSO4, filtered, and concentrated under reduced pressure. The residue was purified via silica gel flash chromatography eluting with 100% DCM to 10% MeOH in DCM to afford 6-((5,6-dimethoxy-1H-benzo[d]imidazol-1-yl)methyl)-2-(methylsulfinyl)benzo[d]oxazole (127 mg, 45%) as a solid. 1H NMR (300 MHz, DMSO-d6) δ 8.24 (s, 1H), 7.85-7.92 (m, 2H), 7.48 (d, J=8.3 Hz, 1H), 7.21 (s, 1H), 7.20 (s, 1H), 5.62 (s, 2H), 3.76 (s, 6H), 3.18 (s, 3H). LCMS (ESI) m/z 372 (M+H)+.

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