Reaction #4204

Reaction equation

hydrochloric acid

4-oxo-5-(phenylmethoxy)-4H-pyran-2-carboxylic acid

ammonium hydroxide

ammonium hydroxide

→

1,4-Dihydro-4-oxo-5-(phenylmethoxy)-2-pyridinecarboxylic acid

Conditions

Workup

1. 1
   workup.STIRRINGThe reaction mixture was then stirred
2. 2
   Temperatureunder reflux
3. 3
   workup.STIRRINGStirring
4. 4
   workup.WAITwas continued for further 2 hours
5. 5
   Temperatureunder reflux
6. 6
   OtherThe reaction solution was then evaporated until the product
7. 7
   Othercrystallized
8. 8
   workup.ADDITIONadded until a clear solution
9. 9
   Otherwas obtained (approximately 5 l, pH 6.38)
10. 10
    workup.ADDITIONwas added dropwise until a pH of 3
11. 11
    Otherwas obtained
12. 12
    OtherThe precipitated white product was removed by filtration
13. 13
    Washthoroughly washed with water
14. 14
    Otherdried

Procedure

300 g (1.22 mol) of 4-oxo-5-(phenylmethoxy)-4H-pyran-2-carboxylic acid was put into a flask and 5 l of 33% ammonium hydroxide was carefully added with stirring. The reaction mixture was then stirred under reflux. After 3 hours, one additional liter of 33% ammonium hydroxide was added slowly. Stirring was continued for further 2 hours under reflux. The reaction solution was then evaporated until the product crystallized. The product was transferred back into the reaction flask and water added until a clear solution was obtained (approximately 5 l, pH 6.38). This solution was stirred vigorously while concentrated hydrochloric acid was added dropwise until a pH of 3 was obtained. The precipitated white product was removed by filtration, thoroughly washed with water and dried. Yield: 273 g.

Source