Reaction #456541

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 solution was heated
2. 2
   Temperatureunder reflux for 30 minutes
3. 3
   TemperatureAfter cooling
4. 4
   Extractionthe resulting 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 removed in vacuo
8. 8
   OtherPurification of the residue by medium pressure liquid column chromatography on silica gel (eluent: hexane/ethyl acetate=7/1)

Procedure

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

Source