Reacción #1551165

Ecuación de reacción

2-(ethoxymethylene)-2-cyanoacetic acid ethyl ester

2-hydrazinopropionaldehyde diethyl acetal

1-(1-methyl-2,2-diethoxyethyl)-4-ethoxycarbonyl-5-aminopyrazole

→

1-(1-methyl-2,2-diethoxyethyl)-4-carboxy-5-aminopyrazole

Rendimiento 11.0%

Disolventes

ethanol

ethanol

sodium hydroxide

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe mixture was refluxed for 4 hours
2. 2
   workup.DISTILLATIONthe solvent was distilled off in vacuo
3. 3
   Otroto give the crude
4. 4
   Temperaturathe mixture was refluxed for 1 hour
5. 5
   TemperaturaThe reaction mixture was cooled at room temperature
6. 6
   Lavadowashed with ethyl acetate (100 ml×2)
7. 7
   FiltraciónThe precipitate was collected by filtration
8. 8
   Lavadowashed with water
9. 9
   Secadodried over phosphorus pentoxide

Procedimiento

To a solution of 2-(ethoxymethylene)-2-cyanoacetic acid ethyl ester (56.3 g) in ethanol (200 ml) was added dropwise 2-hydrazinopropionaldehyde diethyl acetal (54 g) in ethanol (80 ml) at room temperature. The mixture was refluxed for 4 hours. The reaction mixture was cooled at room temperature and the solvent was distilled off in vacuo to give the crude. 1-(1-methyl-2,2-diethoxyethyl)-4-ethoxycarbonyl-5-aminopyrazole (100 g). The crude product (100 g) was dissolved in aqueous 4N-sodium hydroxide (170 ml) and the mixture was refluxed for 1 hour. The reaction mixture was cooled at room temperature and washed with ethyl acetate (100 ml×2). The aqueous solution was adjusted to pH 3.5 with 6N-hydrochloric acid and stirred for 1 hour. The precipitate was collected by filtration, washed with water and dried over phosphorus pentoxide to give 1-(1-methyl-2,2-diethoxyethyl)-4-carboxy-5-aminopyrazole (9.93 g).

Fuente