Water → (2-oxo-4-phenyl-2,6,7,8-tetrahydrocyclopenta[g]chromen-3-yl)acetic Acid

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Reaction Steps

A solution of (6-hydroxy-2,3-dihydro-1H-inden-5-yl)(phenyl)methanone (1.0 g) and triethylamine (0.98 ml) in THF (20 ml) was combined with ethyl succinyl chloride (0.55 ml) at 0° C., and stirred for 1 hour. The reaction solution was combined with water, and the product was extracted with ethyl acetate. The extract was washed with a 1 N solution of hydrochloric acid followed by a saturated aqueous solution of sodium chloride. After drying over magnesium sulfate, the solvent was distilled off under reduced pressure. The resultant residue was dissolved in toluene (10 ml), combined with DBU (0.25 ml), and heated under reflux for 2.5 hours. After cooling, the reaction solution was diluted with ethyl acetate (60 ml), and washed with water followed by a 1 N solution of hydrochloric acid 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 column chromatography (packing: silica gel, eluent: ethyl acetate-hexane=1:2). The resultant crude product of ethyl (2-oxo-4-phenyl-2,6,7,8-tetrahydrocyclopenta[g]chromen-3-yl)acetate was dissolved in acetic acid (20 ml) and concentrated hydrochloric acid (10 ml), and heated under reflux for 1 hour. The reaction solution was concentrated under reduced pressure, and the resultant residue was dissolved in a solvent mixture of THF (5 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 purified by recrystallization from ethyl acetate-isopropyl ether to obtain the title compound (0.95 g, yield: 70%).

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