Reacción #59249

Ecuación de reacción

MgSO4

NaOAc

3-Methyl-2-oxo-butyric acid ethyl ester

butyl-hydrazine oxalate salt

→

crude product ( 3b )

Rendimiento 85.4%

2-(Butyl-hydrazono)-3-methyl-butyric acid ethyl ester

Rendimiento 85.4%

Disolventes

CHCl3

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe mixture was heated
2. 2
   Temperaturato reflux for 3.5 hours under N2 atmosphere
3. 3
   TemperaturaAfter cooling
4. 4
   Filtraciónthe solid was filtered off
5. 5
   Concentraciónthe filtrate was concentrated under reduced vacuum
6. 6
   ExtracciónThe residue was first cleaned by an extraction between EtOAc (50 mL×3) and H2O (20 mL)
7. 7
   ConcentraciónThe organic layer was concentrated under reduced pressure
8. 8
   Otrodried under high vacuum overnight

Procedimiento

To a solution of 3-Methyl-2-oxo-butyric acid ethyl ester (1c) (1.88 g, 13.04 mmol) in 45 mL of CHCl3, butyl-hydrazine oxalate salt (2.11 g, 11.85 mmol) was added followed by NaOAc (1.94 g, 23.4 mmol) and MgSO4 (1.43 g, 11.88 mmol). The mixture was heated to reflux for 3.5 hours under N2 atmosphere with stirring. After cooling, the solid was filtered off and the filtrate was concentrated under reduced vacuum. The residue was first cleaned by an extraction between EtOAc (50 mL×3) and H2O (20 mL). The organic layer was concentrated under reduced pressure and dried under high vacuum overnight to give 2.17 g of the crude product (3b) in 85.4% yield as a mixture of the E- and Z-isomers. This crude product was directly used in the next step without further purification. LC-MS (ESI+): m/e=215.4 [M+1]+, 237.1 [M+Na]+ (exact ms: 214.17).

Fuente