反应详情

To a solution of 15.9 g of a mixture of 4-fluoro-5-methyl-benzo[b]thiophene and 6-fluoro-5-methyl-benzo[b]thiophene in 160 ml of carbon tetrachloride are added 17 g of N-bromosuccinimide and 0.31 g of 2,2'-azo-bisisobutylonitrile. The resulting mixture is refluxed for two hours. After cooling, insolubles are removed from the thus cooled mixture by filtration, and the filtrate obtained is concentrated under reduced pressure. The residue obtained is suspended in 75 ml of acetic acid and 75 ml of water, and 26.8 g of hexamethylenetetramine is added thereto, after which the resulting mixture is refluxed for two hours. After cooling, 150 ml of water and 200 ml of ethyl acetate are added to the thus cooled mixture, and the resulting organic layer is separated, washed successively with water, an aqueous saturated sodium carbonate solution and a saturated saline solution and then dried over anhydrous magnesium sulfate. Thereafter, the solvent is removed from the thus dried layer by distillation under reduced pressure. The residue thus obtained is purified by a moderate pressure column chromatography [eluent: hexane:ethyl acetate=15:1], to obtain 1.71 g of 4-fluorobenzo[b]thiophene-5-carbaldehyde and 5.82 g of 6-fluorobenzo[b]thiopene-5-carbaldehyde.

1. temperatureThe resulting mixture is refluxed for two hours
2. temperatureAfter cooling
3. custominsolubles are removed from the thus cooled mixture by filtration
4. customthe filtrate obtained
5. concentrationis concentrated under reduced pressure
6. customThe residue obtained
7. temperatureafter which the resulting mixture is refluxed for two hours
8. temperatureAfter cooling
9. customthe resulting organic layer is separated
10. washwashed successively with water
11. dry with materialan aqueous saturated sodium carbonate solution and a saturated saline solution and then dried over anhydrous magnesium sulfate
12. customThereafter, the solvent is removed from the thus dried layer by distillation under reduced pressure
13. customThe residue thus obtained
14. customis purified by a moderate pressure column chromatography [eluent: hexane:ethyl acetate=15:1]