Hydrochloric Acid → 4-Cyano-7-fluoro-5-methyl-6-phenyl-1,3-benzoxazole-2-carboxamide

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Reaction Steps

At room temperature, trimethylaluminium (4.49 ml, 4.63 mmol, 1.03 M hexane solution was added to an anhydrous dichloromethane (6 ml) suspension of ammonium chloride (247 mg, 4.62 mmol), followed by stirring at room temperature for 20 minutes. A dichloromethane (4 ml) solution of ethyl 4-cyano-7-fluoro-5-methyl-6-phenyl-1,3-benzoxazole-2-carboxylate (I-111) (500 mg, 1.54 mmol) was added, followed by stirring for 4 hours and by heating under reflux in an oil bath at 45° C. for 48 hours. With cooling with ice, 1 N hydrochloric acid (10 ml) was added to the reaction liquid, then water (20 ml) was added, followed by extraction with chloroform (100 ml×2). The organic layer was washed with saturated brine (100 ml), then dried over anhydrous sodium sulfate, concentrated under reduced pressure, and the resulting residue was purified in slurry with diethyl ether to obtain the entitled compound (368 mg, 80.8%) as a pale yellow solid.

Provenance & Evidence