反应详情

300 g of polyphosphoric acid was added to 99.24 g (0.40 mole) of the 3-(3,4-dichloroanilino)butyric acid and this mixture was stirred at 90°-100° C. for 4 hours. After being allowed to cool to room temperature, the resulting reaction solution was diluted with 3 liters of water and then adjusted to pH 4-5 with an aqueous sodium hydroxide solution. Then, the solid matter which separated out was extracted with chloroform and this extract was concentrated under reduced pressure. The residue thus obtained was purified by silica gel column chromatography (using chloroform as the developing solvent). The fraction containing the desired product was evaporated to dryness under reduced pressure and the resulting residue was recrystallized from benzene to obtain 9.94 g (10.8% yield) of 5,6-dichloro-2-methyl-4-oxo-1,2,3,4-tetra-hydroquinoline in the form of yellow crystals. On the other hand, another fraction was worked up in the same manner as above to obtain 13.53 g (14.7% yield) of a structural isomer thereof, or 6,7-dichloro-2-methyl- 4-oxo-1,2,3,4-tetrahydroquinoline, in the form of yellow crystals.

1. customthe resulting reaction solution
2. customThen, the solid matter which separated out
3. extractionwas extracted with chloroform
4. concentrationthis extract was concentrated under reduced pressure
5. customThe residue thus obtained
6. customwas purified by silica gel column chromatography (
7. additionThe fraction containing the desired product
8. customwas evaporated to dryness under reduced pressure
9. customthe resulting residue was recrystallized from benzene