反应详情

Ozone was conducted into a solution of 8.0 g (35 mmol) of 7-bromo-4-fluoro-2-methylbenzofuran at -78° C. until the colour became blue. Subsequently, argon was conducted through the solution which was then treated at -78° C. with 13 ml of dimethyl sulfide. After warming to room temperature the solution was concentrated in a vacuum and the residue was dissolved in 50 ml of ethanol. After the addition of 50 ml of 3% sodium hydrogen carbonate solution the mixture was stirred at 70° for 30 minutes. Subsequently, the mixture was poured on to 200 ml of ice-water, made acid with 10% HCl and extracted three times with 150 ml of diethyl ether. After drying over sodium sulfate concentration was carried out in a vacuum. The crude product obtained was purified by column chromatography on silica gel (dichloromethane/hexane 4:1). There were obtained 7.5 g (98%) of 3-bromo-6-fluoro-2-hydroxy-benzaldehyde as a pale yellow oil, which was used immediately in the next reaction.

1. concentrationwas concentrated in a vacuum
2. dissolutionthe residue was dissolved in 50 ml of ethanol
3. additionAfter the addition of 50 ml of 3% sodium hydrogen carbonate solution the mixture
4. additionSubsequently, the mixture was poured on to 200 ml of ice-water
5. extractionextracted three times with 150 ml of diethyl ether
6. dry with materialAfter drying over sodium sulfate concentration
7. customThe crude product obtained
8. customwas purified by column chromatography on silica gel (dichloromethane/hexane 4:1)