Sulfuric acid magnesium salt (1:1) → 2-(Butyl-hydrazono)-3-methyl-butyric acid ethyl ester

Beteiligte Stoffe

Reaktionsschritte

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).

Herkunft & Nachweise