Hydrochloric Acid → ethyl 5,6-dihydro-9-methyl-6-oxo-4H-pyrrolo [3,2,1-ij]quinoline-2-carboxylate

A mixture of ethyl 1-(2-carboxyethyl)- 4-methyl-1H-indole-2-carboxylate (1.00 g, 3.63 mmol), thionyl chloride (1.35 g, 11.4 mmol) and chloroform (16 ml) was heated under reflux for 5 hours. The reaction mixture was concentrated under reduced pressure and dichloromethane (80 ml) was added to the residue, followed by stirring at room temperature. Subsequently, aluminum chloride (2.02 g, 15.1 mmol) was added and the resulting mixture was stirred at room temperature for 1.5 hours and then heated under reflux for 0.5 hour. The reaction mixture was added to a mixture of water (300 ml) and 35% hydrochloric acid (1.5 ml), followed by extraction with chloroform (three times). The extract solution was washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure and the resulting residue was purified by a silica gel column chromatography (eluent: ethyl acetate/n-hexane=3/97) to obtain ethyl 5,6-dihydro-9-methyl-6-oxo-4H-pyrrolo-[3,2,1-ij]quinoline-2-carboxylate (0.53 g).

1. temperaturewas heated
2. temperatureunder reflux for 5 hours
3. concentrationThe reaction mixture was concentrated under reduced pressure and dichloromethane (80 ml)
4. additionwas added to the residue
5. stirringthe resulting mixture was stirred at room temperature for 1.5 hours
6. temperatureheated
7. temperatureunder reflux for 0.5 hour
8. extractionfollowed by extraction with chloroform (three times)
9. washThe extract solution was washed with water
10. dry with materialdried over anhydrous magnesium sulfate
11. distillationThe solvent was distilled off under reduced pressure
12. customthe resulting residue was purified by a silica gel column chromatography (eluent: ethyl acetate/n-hexane=3/97)

ORD record

ord-c3d7bb044380402e9ff549d70e564abb

Source dataset

uspto-grants-1998_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05834454