Hydrochloric Acid → 7,8-Diacetoxy-3,4-diphenylcoumarin

Participants

Reaction Steps

To a solution of 821 mg (5.0 mmol) of ethyl phenylacetate (purchased from Tokyo Kasei) in 2 ml of ethanol (purchased from Kokusan Kagaku) was added a solution of 0.8 g of sodium hydroxide dissolved in 2 ml of water, and the mixture was stirred at room temperature for 2 hours. To the mixture was added 30 ml of about 10% hydrochloric acid, the mixture was extracted with ether three times, the organic layer was washed with brine and dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. To the residue were added 1.15 g (5.0 mmol) of 2,3,4-trihydroxybenzophenone (purchased from Tokyo Kasei) and 10 ml of acetic anhydride (purchased from Wako Junyaku), and then 5 ml of triethylamine (purchased from Kokusan Kagaku) was added to the mixture under stirring and ice-cooling, and the mixture was stirred for 1 hour. Subsequently, the resultant mixture was refluxed for 2 hours in an oil bath heated at 120° C. After being cooled, the resultant mixture was added to 100 ml of 10% hydrochloric acid ice-cooled, stirred for a while and extracted with methylene chloride three times. The organic layer was washed with aqueous sodium hydrogencarbonate and subsequently with brine and dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure. The residue as an oil was purified by column chromatography on silica gel (ethyl acetate:hexane=1:2 as an eluent) to give 823 mg (yield: 39.8%) of 7,8-diacetoxy-3,4-diphenylcoumarin as a white crystalline. To 250 mg (0.6 mmol) of the above 7,8-diacetoxy-3,4-diphenylcoumarin were added 8 ml of ethanol, 1 ml of water and 1 ml of concentrated hydrochloric acid, and the mixture was refluxed for 4 hours. After being cooled, the resultant mixture was added to 60 ml of water, and the precipitate was collected, washed with water and dried to give 165 mg (yield: 82.8%) of the compound as a white crystalline represented by the following formula: ##STR122## melting point of the obtained compound was 281°-282° C.

Provenance & Evidence