Reaction #454513

Reaction equation

sodium bicarbonate

2-Bromo-4'-hydroxy-3'-hydroxymethylacetophenone

p-toluenesulfonic acid monohydrate

acetone dimethyl acetal

→

2-bromo-1-(2,2-dimethylbenzo[1,2-d]-1,3-dioxan-6-yl)-1-ethanone

Solvents

acetone

Conditions

Workup

1. 1
   Temperaturethe mixture was heated
2. 2
   Temperatureunder reflux for 30 minutes
3. 3
   TemperatureAfter cooling
4. 4
   Extractionthe mixture was extracted with ethyl acetate
5. 5
   WashThe extract was washed with water and brine
6. 6
   Dryingdried over anhydrous magnesium sulfate
7. 7
   OtherThe solvent was evaporated under reduced pressure
8. 8
   Otherthe resulting residue was purified by silica gel medium pressure liquid column chromatography (eluent: hexane/ethyl acetate=7/1)

Procedure

2-Bromo-4'-hydroxy-3'-hydroxymethylacetophenone (17.7 g), 124 mg of p-toluenesulfonic acid monohydrate and 256 ml of acetone dimethyl acetal were dissolved in 256 ml of acetone and the mixture was heated under reflux for 30 minutes. After cooling, an aqueous saturated sodium bicarbonate solution was added to the reaction solution, and the mixture was extracted with ethyl acetate. The extract was washed with water and brine and then dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure and the resulting residue was purified by silica gel medium pressure liquid column chromatography (eluent: hexane/ethyl acetate=7/1) to give 11.9 g of 2-bromo-1-(2,2-dimethylbenzo[1,2-d]-1,3-dioxan-6-yl)-1-ethanone having a melting point of 52 to 54° C.

Source