Ethanol → 3-(3,4-dihydroxycinnamoylamino)-4-(2-methylphenyl)-7,8-dihydrocyclopenta[g][1]benzopyran-2(6H)-one

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Reaction Steps

To a solution of 3-(3,4-dimethoxycinnamoylamino)-4-(2-methylphenyl)-7,8-dihydrocylopenta[g][1]benzopyran-2(6H)-one (400 mg) in dichloromethane (6 ml) was added boron tribromidedichloromethane (1:2, 1 ml) dropwise with ice-cooling and stirring. The mixture was further stirred under ice-cooling for 1 hour and, then, added gradually to ethanol (5 ml) with ice-cooling. The mixture was diluted with water and extracted with ethyl acetate, the extract was washed with water and dried (MgSO4), and the solvent was distilled off to give crystals of 3-(3,4-dihydroxycinnamoylamino)-4-(2-methylphenyl)-7,8-dihydrocyclopenta[g][1]benzopyran-2(6H)-one (361 mg, 95.8%). Recrystallization from ethanol gave light brown prisms, m.p. 295°-297° C.

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