Reaction #2856

Reaction equation

3-thiophene-2-yl-acrylic acid

triethylamine

tributylamine

sodium azide

ethyl chloroformate

→

title compound

Yield 49.7%

5H-Thieno[3,2-c]pyridin-4-one

Yield 49.7%

Solvents

acetone

diphenyl ether

H2O

—

hexanes

H2O

Conditions

Workup

1. 1
   FiltrationA white precipitate forms which is collected by filtration
2. 2
   DryingThe resulting solid is dried over P2O5 under vacuum
3. 3
   workup.WAITAfter 2 h
4. 4
   Temperaturethe solution is cooled to ambient temperatures
5. 5
   Temperatureis cooled to 0° C
6. 6
   FiltrationThe resulting solid is collected by filtration
7. 7
   Washthe solid is washed with hexanes

Procedure

To a solution of 3-thiophene-2-yl-acrylic acid (7.39 g, 47.9 mmol) in 200 mL of acetone is added triethylamine (4.9 g, 47.9 mmol). The resulting solution is cooled to 0° C. and ethyl chloroformate (5.7 g, 52.8 mmol) is added dropwise. After 2 h, sodium azide (4.67 g, 71.9 mmol) in 25 mL of H2O is then added. The solution is stirred for 1.5 h at 0° C. After this time, the solution is poured into 300 mL of H2O. A white precipitate forms which is collected by filtration. The resulting solid is dried over P2O5 under vacuum. The solid is suspended in 20 mL of diphenyl ether. This solution is added dropwise to a solution of tributylamine (6.9 g, 37.4 mmol) in 200 ml of diphenyl ether at 190° C. After 2 h, the solution is cooled to ambient temperatures. The solution is diluted with 1000 mL of hexanes and is cooled to 0° C. The resulting solid is collected by filtration and the solid is washed with hexanes. The title compound (3.6 g, 23.8 mmol) is obtained as a white solid.

Source