7,8-dichloro-2,3-dihydrochromen-4-one

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 100 mg. (0.46 mmol) 7,8-dichlorochroman-4-one was dissolved in anhydrous ethanol (5 ml) and Chloroform (5 ml). To this solution was added pyridinium tribromide (0.442 g, 1.38 mmol, 3 equiv). The reddish brown mixture was heated with stirring at 50 C for 30 min. The reaction mixture was then cooled and the solvent was evaporated. Then water (20 ml) was added to the residue and it was then extracted with 20 ml of dichloromethane. The dichloromethane layer was then washed with 5% sodium bicarbonate solution followed by water (20 ml). The organic layer was then dried and the solvent was evaporated in vacuum to yield the crude product which was purified by column chromatography. A mixture of 100 mg The reddish brown mixture was heated The reaction mixture was then cooled the solvent was evaporated Then water (20 ml) was added to the residue and it was then extracted with 20 ml of dichloromethane The dichloromethane layer was then washed with 5% sodium bicarbonate solution The organic layer was then dried the solvent was evaporated in vacuum

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 100 mg. (0.46 mmol) 7,8-dichlorochroman-4-one was dissolved in anhydrous ethanol (5 ml) and Chloroform (5 ml). To this solution was added pyridinium tribromide (0.442 g, 1.38 mmol, 3 equiv). The reddish brown mixture was heated with stirring at 50 C for 30 min. The reaction mixture was then cooled and the solvent was evaporated. Then water (20 ml) was added to the residue and it was then extracted with 20 ml of dichloromethane. The dichloromethane layer was then washed with 5% sodium bicarbonate solution followed by water (20 ml). The organic layer was then dried and the solvent was evaporated in vacuum to yield the crude product which was purified by column chromatography. A mixture of 100 mg The reddish brown mixture was heated The reaction mixture was then cooled the solvent was evaporated Then water (20 ml) was added to the residue and it was then extracted with 20 ml of dichloromethane The dichloromethane layer was then washed with 5% sodium bicarbonate solution The organic layer was then dried the solvent was evaporated in vacuum

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 500 mg of 3-(2,3-dichlorophenoxy)propionic acid, is stirred in 50 ml. of liquid hydrogen fluoride surrounded by a solid carbon dioxide/acetone bath. This slurry is allowed to stir overnight without replenishing the cooling bath. The hydrogen fluoride is removed by a stream of air. The residual solid was then dissolved in ether and washed with 10% aqueous sodium carbonate solution. The organic layer is dried over anhydrous magnesium sulphate and the solvent is evaporated to give the required chromanone with sufficient purity. The hydrogen fluoride is removed by a stream of air The residual solid was then dissolved in ether washed with 10% aqueous sodium carbonate solution The organic layer is dried over anhydrous magnesium sulphate the solvent is evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 100 mg. (0.46 mmol) 7,8-dichlorochroman-4-one was dissolved in anhydrous ethanol (5 ml) and Chloroform (5 ml). To this solution was added pyridinium tribromide (0.442 g, 1.38 mmol, 3 equiv). The reddish brown mixture was heated with stirring at 50 C for 30 min. The reaction mixture was then cooled and the solvent was evaporated. Then water (20 ml) was added to the residue and it was then extracted with 20 ml of dichloromethane. The dichloromethane layer was then washed with 5% sodium bicarbonate solution followed by water (20 ml). The organic layer was then dried and the solvent was evaporated in vacuum to yield the crude product which was purified by column chromatography. A mixture of 100 mg The reddish brown mixture was heated The reaction mixture was then cooled the solvent was evaporated Then water (20 ml) was added to the residue and it was then extracted with 20 ml of dichloromethane The dichloromethane layer was then washed with 5% sodium bicarbonate solution The organic layer was then dried the solvent was evaporated in vacuum

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 500 mg of 3-(2,3-dichlorophenoxy)propionic acid, is stirred in 50 ml. of liquid hydrogen fluoride surrounded by a solid carbon dioxide/acetone bath. This slurry is allowed to stir overnight without replenishing the cooling bath. The hydrogen fluoride is removed by a stream of air. The residual solid was then dissolved in ether and washed with 10% aqueous sodium carbonate solution. The organic layer is dried over anhydrous magnesium sulphate and the solvent is evaporated to give the required chromanone with sufficient purity. The hydrogen fluoride is removed by a stream of air The residual solid was then dissolved in ether washed with 10% aqueous sodium carbonate solution The organic layer is dried over anhydrous magnesium sulphate the solvent is evaporated