Hydrochloric Acid → 2-[6-(bromomethyl)-7-chloro-2-oxo-4-phenyl-2H-chromen-3-yl]acetic acid

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Reaction Steps

A solution of ethyl(7-chloro-6-methyl-2-oxo-4-phenyl-2H-chromen-3-yl)acetate (3.5 g) in ethyl acetate (50 ml) was combined with N-bromosuccinimide (2.1 g) and 2,2′-azoisobutyronitrile (48.3 mg), and heated under reflux for 1 hour. After cooling, the reaction solution was washed with water followed by a saturated aqueous solution of sodium hydrogen carbonate and a saturated aqueous solution of sodium chloride. After drying over magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by a silica gel column chromatography (eluent: ethyl acetate-hexane=1:4) to obtain the crude crystal (approximately 2.6 g) of ethyl 2-[6-(bromomethyl)-7-chloro-2-oxo-4-phenyl-2H-chromen-3-yl]acetate. The crude crystal was dissolved in acetic acid (50 ml) and concentrated hydrochloric acid (25 ml), and heated under reflux for 30 minutes. The reaction solution was concentrated under reduced pressure, and the resultant residue was dissolved in a solvent mixture of THF (10 ml) and ethyl acetate (50 ml), and then washed with water followed by a saturated aqueous solution of sodium hydrogen carbonate and a saturated aqueous solution of sodium chloride. After drying over magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was washed with ethyl acetate to obtain a crude crystal (1.78 g, yield: 44%) of the title compound. The compound was used in the next reaction without further purification. NMR (CDCl3) δ: 3.43 (2H, s), 4.58 (2H, s), 7.11 (1H, s), 7.20-7.30 (2H, m), 7.48 (1H, s), 7.50-7.65 (3H, m).

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