Ammonium Chloride → 2-Cyclopropyl-6-(2,3-difluorophenyl)-7-fluoro-5-methyl-1,3-benzoxazole-4-carbonitrile

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6-Bromo-2-cyclopropyl-7-fluoro-5-methyl-1,3-benzoxazole-4-carbonitrile (I-77) (190 mg, 0.64 mmol), 2,3-difluorophenylboronic acid (407 mg, 2.58 mmol) and tripotassium phosphate (274 mg, 1.29 mmol) were dissolved in 1,4-dioxane (6 ml), then at room temperature, tetrakis(triphenylphosphine)palladium(0) (149 mg, 0.13 mmol) was added. The suspension was stirred under nitrogen atmosphere at 95° C. for 86 hours. After cooling to room temperature, the solution was fractionated with ethyl acetate and aqueous saturated ammonium chloride solution. The aqueous layer was extracted twice with ethyl acetate. The organic layers were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. The solvent was evaporated away, and the resulting residue was purified by middle-pressure liquid chromatography (eluent, hexane:ethyl acetate=9:1) to obtain the entitled compound (111 mg, 53%) as a white solid.

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