3',5-Dimethoxy[1,1'-biphenyl]-2-carboxylic acid → 3,6-Dimethoxyfluoren-9-one

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Reaction Steps

7.5 g of 2-carboxy-5,5'-dimethoxybiphenyl was dissolved in 75 mL of methanesulfonic acid to obtain a dark brown solution. The solution was stirred at room temperature for one hour, heated at 40°-50° C. for 5 hours and then cooled to room temperature. The reaction mixture was then poured onto crushed ice to form a yellow colored precipitate which was collected by filtration. The precipitate was washed with large amounts of water and then air dried to yield 6.7 g of crude 3,6-dimethoxy-9-fluorenone. Recrystallization from ethanol followed by column chromatography on silica gel using methylene chloride as the eluent yielded pure 3,6-dimethoxy-9-fluorenone. The structure was confirmed by NMR and mass spectroscopy.

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