p-Toluenesulfonic acid monohydrate → 2-Tert-butyl-7-fluoro-5-methyl-6-phenyl-1,3-benzoxazole-4-carbonitrile

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Reaction Steps

Toluene (67 ml), p-toluenesulfonic acid monohydrate (98 mg, 515 μmol) were added to N-(5-cyano-2-fluoro-3-hydroxy-6-methylbiphenyl-4-yl)-2,2-dimethylpropionamide (I-73) (1.68 g, 5.15 mmol), followed by refluxing with a Dean-Stark condenser for 4 hours. After cooling, saturated sodium bicarbonate water (50 ml) was added to the reaction liquid, the product was extracted with ethyl acetate (200 ml). The organic layer was washed with saturated brine (50 ml×2), then dried over anhydrous magnesium sulfate, concentrated under reduced pressure, the residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=6:1) to obtain the entitled compound (1.44 g, 91%) as a colorless solid.

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