Trifluoroacetic acid → 6-Amino-2-cyclopropyl-7-fluoro-5-methyl-1,3-benzoxazole-4-carbonitrile

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Reaction Steps

tert-Butyl (4-cyano-2-cyclopropyl-7-fluoro-5-methyl-1,3-benzoxazol-6-yl)carbamate (I-319) (40 mg, 0.12 mmol) was dissolved in dichloromethane (1 ml), then at room temperature, trifluoroacetic acid (1 ml) was added. The solution was stirred at the same temperature for 6 hours, then the solvent was evaporated away under reduced pressure, and the residue was fractionated with dichloromethane and an aqueous saturated sodium hydrogencarbonate solution. The aqueous layer was further extracted twice with dichloromethane. The organic layers were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. The insoluble matter was separated by filtration, then the solvent was evaporated away, and the resulting residue was purified by middle-pressure liquid chromatography (eluent, n-hexane:ethyl acetate=2:1, v/v) to obtain the entitled compound (27 mg, 97%) as a pale brown solid.

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