Reaction #2460288

Reaction equation

1-ethynylnaphthalene

1,2,2,6,6-pentamethylpiperidine

ethyl chloroformate

→

ethyl 1-naphthylpropiolate

Yield 36.0%

Solvents

acetonitrile

—

ligroin

Conditions

Workup

1. 1
   OtherFirst, ethyl 1-naphthylpropiolate was prepared
2. 2
   Otherwas sparged with nitrogen for 10 min
3. 3
   OtherThe mixture was sparged with nitrogen for 10 min
4. 4
   Temperatureheated
5. 5
   Temperatureto reflux
6. 6
   Temperatureat reflux for 2 h
7. 7
   TemperatureThe reaction mixture was cooled to ambient and
8. 8
   WashThe solution was washed three times with water
9. 9
   Dryingwith brine, dried (Na2SO4)
10. 10
    Concentrationconcentrated
11. 11
    OtherThe crude product was purified by column chromatography

Procedure

First, ethyl 1-naphthylpropiolate was prepared. A mixture of 1-ethynylnaphthalene (7.7 g, 50.6 mmol), 4-(dimethylamino)pyridine (0.06 g, 0.5 mmol), 1,2,2,6,6-pentamethylpiperidine (8.8 g, 55.7 mmol), and acetonitrile (120 mL) was sparged with nitrogen for 10 min, and then tetrakis(triphenylphosphine)palladium(0) (1.3 g, 1.1 mmol) was added. The mixture was sparged with nitrogen for 10 min, heated to reflux, treated dropwise with ethyl chloroformate (12.1 g, 111.3 mmol), and held at reflux for 2 h. The reaction mixture was cooled to ambient and diluted with ligroin. The solution was washed three times with water and then with brine, dried (Na2SO4), and concentrated to deposit a brown oil. The crude product was purified by column chromatography to provide 4.0 g (36% of theory) of ethyl 1-naphthylpropiolate. 1H NMR (CDCl3): δ 1.40 (t, 3H), 4.33 (q, 2H), 7.50 (m, 3H), 7.90 (m, 3H), 8.30 (d, 1H).

Source