Acetic Acid → 1-(1-Ethyl-4-hydroxy-5-methyl-1H-pyrazol-3-yl)ethanone

Reaktionsgleichung

[CH3:1][C:2]([CH:4]=O)=[O:3].[C:6]([OH:11])(=O)[C:7](O)=O.[CH2:12]([NH:14][NH2:15])[CH3:13].[C:16](O)(=O)C>O>[CH2:12]([N:14]1[C:7]([CH3:16])=[C:6]([OH:11])[C:4]([C:2](=[O:3])[CH3:1])=[N:15]1)[CH3:13]

Komponenten

Versuchsvorschrift

An aqueous solution of methyl glyoxal (pyruvaldehyde) (40%, 6.5 mL, 40 mmol) was added to a solution of ethylhydrazine oxalate (1 g, 6.7 mmol) and acetic acid (0.57 mL, 10 mmol) in water (11 mL), and the resulting mixture was heated at reflux for 3 hours. The reaction mixture was cooled to room temperature and extracted with EtOAc (3×). The combined organic layers were dried, filtered, and concentrated under reduced pressure. The crude product was purified by flash chromatography (silica gel) eluting with a gradient of heptane to heptane:ethyl acetate (80:20) to give 622 mg (56%) of 1-(1-ethyl-4-hydroxy-5-methyl-1H-pyrazol-3-yl)ethanone as a white solid.