Reaction #59249

Reaction equation

MgSO4

NaOAc

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

butyl-hydrazine oxalate salt

→

crude product ( 3b )

Yield 85.4%

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

Yield 85.4%

Solvents

CHCl3

Conditions

Workup

1. 1
   TemperatureThe mixture was heated
2. 2
   Temperatureto reflux for 3.5 hours under N2 atmosphere
3. 3
   TemperatureAfter cooling
4. 4
   Filtrationthe solid was filtered off
5. 5
   Concentrationthe filtrate was concentrated under reduced vacuum
6. 6
   ExtractionThe residue was first cleaned by an extraction between EtOAc (50 mL×3) and H2O (20 mL)
7. 7
   ConcentrationThe organic layer was concentrated under reduced pressure
8. 8
   Otherdried under high vacuum overnight

Procedure

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).

Source