2-Aminophenol → 2-[4-Methyl-3-(trifluoromethyl)phenyl]-1,3-benzoxazole

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A mixture of 4-methyl-3-(trifluoromethyl)benzoic acid (1.0 g, 4.9 mmol) and thionyl chloride (15 mL) was refluxed for 3 h and then stirred at rt overnight. The excess thionyl chloride was removed in vacuo, the residue was dissolved in THF (20 mL), and it was added to a cooled (0° C.) solution of 2-aminophenol (0.53 g, 4.9 mmol) and diisopropylethylamine (1.0 mL, 5.9 mmol) in anhydrous THF (15 mL). The resulting brownish mixture was stirred at rt for 3 h. The solvent was then removed and p-toluenesulfonic acid (3.7 g, 19.6 mmol) and toluene (20 mL) were added to the dark oil. The mixture was then refluxed for 3 h and the mixture was cooled to rt. The excess p-toluenesulfonic acid was filtered through Celite and the filtrate was evaporated to dryness. The crude was purified by flash chromatography on silica gel eluting with EtOAc:hexanes (1:9) to afford 2-[4-methyl-3-(trifluoromethyl)phenyl]-1,3-benzoxazole as a colorless solid.

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