Reaction #5394

Reaction equation

2-carboxy-5,5'-dimethoxybiphenyl

→

3,6-dimethoxy-9-fluorenone

Yield 96.0%

Solvents

methanesulfonic acid

Conditions

Workup

1. 1
   Otherto obtain a dark brown solution
2. 2
   Temperatureheated at 40°-50° C. for 5 hours
3. 3
   Temperaturecooled to room temperature
4. 4
   workup.ADDITIONThe reaction mixture was then poured
5. 5
   Otheronto crushed ice
6. 6
   Otherto form a yellow colored precipitate which
7. 7
   Filtrationwas collected by filtration
8. 8
   WashThe precipitate was washed with large amounts of water
9. 9
   Otherair dried

Procedure

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.

Source