Reaction #155320

Reaction equation

3-propoxynaphthalen-2-ylamine

ethyl α-(hydroxymethylene)-4-methoxyphenylacetate

→

2-(4-methoxyphenyl)-5-propoxy-4H-benzo[f]quinolin-1-one

Yield 42.4%

Solvents

benzene

Conditions

Workup

1. 1
   workup.ADDITIONwas added 350 mg of Amberlyst 15 (Sigma-Aldrich)
2. 2
   TemperatureThe resulting mixture was heated
3. 3
   Temperatureunder reflux for 21 hours
4. 4
   Filtrationfiltered
5. 5
   Otherto remove resin
6. 6
   Concentrationthe filtrate was concentrated under reduced pressure
7. 7
   workup.ADDITIONDiphenyl ether (2.2 ml) was added to the residue
8. 8
   Temperaturethe mixture was then heated with a mantle heater
9. 9
   Temperatureunder reflux
10. 10
    OtherThe resulting reaction mixture
11. 11
    Temperaturewas cooled to room temperature
12. 12
    Otherdirectly purified
13. 13
    ConcentrationThe purified product was concentrated under reduced pressure
14. 14
    Otherto recrystallize the residue from ethyl acetate-n-hexane

Procedure

To a benzene solution (50 ml) containing 3-propoxynaphthalen-2-ylamine (2.05 g, 10.18 mmol) and ethyl α-(hydroxymethylene)-4-methoxyphenylacetate (2.29 g, 10.3 mmol) was added 350 mg of Amberlyst 15 (Sigma-Aldrich). The resulting mixture was heated under reflux for 21 hours using a Dean-Stark trap. The reaction mixture was then cooled to room temperature, filtered to remove resin, and then the filtrate was concentrated under reduced pressure. Diphenyl ether (2.2 ml) was added to the residue, and the mixture was then heated with a mantle heater and stirred for 1.5 hours under reflux. The resulting reaction mixture was cooled to room temperature, and then directly purified using silica gel column chromatography (dichloromethane:methanol=100:1→60:1). The purified product was concentrated under reduced pressure to recrystallize the residue from ethyl acetate-n-hexane, giving a pale yellow powder of 2-(4-methoxyphenyl)-5-propoxy-4H-benzo[f]quinolin-1-one (1.55 g, yield: 42%).

Source