Triethylamine → Ethyl (3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)acetate

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Reaction Steps

To an ethanol (250 mL) solution of ethyl hydrazinoacetate monohydrochloride (19.4 g, 125 mmol) was added triethylamine (19.2 mL, 138 mmol), and the mixture was stirred at room temperature for 10 minutes, and then ethyl acetoacetate (16.6 mL, 131 mmol) was added, and the mixture was heated to reflux for four hours. After returning the mixture to room temperature, the solvent was distilled off under reduced pressure. N-heptane (100 mL) was added to the residue to yield a solid, and the obtained solid was filtered and washed with n-heptane to obtain primary crystals of the title compound (17.1 g, 93.0 mmol). Furthermore, the solvent in the filtrate was distilled off under reduced pressure, and to the residue, n-heptane/acetone mixture (1:1) was added to yield a solid, and the obtained solid was filtered. Thus, secondary crystals of the title compound (0.44 g, 2.39 mmol) were obtained.

Provenance & Evidence