Acetic Acid → 4-(2,3-Difluoro-phenyl)-1,3-dihydro-indol-2-one

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Reaction Steps

4-(2,3-difluoro-phenyl)-1H-indole 6c (744 mg, 3.25 mmol) was dissolved in 12 ml of ethanol under stirring, and added successively with tert-butanol (21 ml), glacial acetic acid (6.4 ml) and pyridinium tribromide (3.12 g, 9.7 mmol) at room temperature. Upon completion of the addition, the reaction mixture was stirred for 3 hours, added with glacial acetic acid (16 ml) and zinc dust (1.1 g, 16.25 mmol), and stirred for another 1 hour. The reaction mixture was filtered and concentrated under reduced pressure. The residue was added with ethyl acetate (30 ml), washed successively with water (10 ml), saturated sodium bicarbonate solution (10 ml) and saturated brine (10 ml), dried over anhydrous sodium sulfate, filtered to remove the drying agent and concentrated under reduced pressure to obtain 4-(2,3-difluoro-phenyl)-1,3-dihydro-indol-2-one 6d (780 mg, yield 97%) as a white solid.

Provenance & Evidence