Triethylamine → 5-(4-bromo-2-chlorophenyl)-4-fluoro-5H-imidazo[4',5':4,5]benzo[1,2-d]oxazol-6(7H)-one

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Reaction Steps

To a solution of 5-((4-bromo-2-chlorophenyl)amino)-4-fluorobenzo[d]oxazole-6-carboxylic acid (110 mg, 0.28 mmol) in t-BuOH (3 mL) was added DPPA (94 mg, 0.34 mmol) followed by triethylamine (58 mg, 0.57 mmol). The mixture was heated under reflux for 3 h and allowed to slowly warm to room temperature. The solvent was removed in vacuo and the resultant crude product was purified by column chromatography on silica gel (petroleum ether/ethyl acetate, 2:1, v/v). The corresponding product was obtained (white solid, 105 mg, 96.2% yield). 1H NMR (400 MHz, DMSO-d6): δ 11.78 (s, 1H), 8.69 (s, 1H), 7.99 (d, 1H), 7.77 (d, 1H), 7.51 (m, 1H), 7.41 (s, 1H).

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