Methylhydrazine → Ethyl 5-ethyl-1-methyl-1H-pyrazole-3-carboxylate

Participants

Reaction Steps

Ethyl 2,4-dioxohexanoate (12 g) in glacial acetic acid (75 ml) was cooled in an ice-bath and treated with methylhydrazine (3.21 g) in a dropwise fashion over 5-10 m. On complete addition the ice cooling was removed and the yellow homogeneous solution stirred at room temperature for ca. 2 h. The acetic acid was then removed in vacuo and the residual oil re-dissolved in ethyl acetate (- 100 mls). The ethyl acetate solution was washed with saturated sodium hydrogen carbonate (3×) and brine. After drying over anhydrous magnesium sulphate the solvent was evaporated. The crude material was purified by silica gel chromatography eluting with 20-70% ethyl acetate/hexane giving the title compound as a pale yellow oil, (6.656 g, 52%); dH (CDCl3) 1.28 (3H, t, J7.6 Hz), 1.38 (3H, t, 37.1 Hz), 2.61 (2H, q, J7.6 Hz), 3.84 (3H, s), 4.38 (2H, q, J7.1 Hz) and 6.58 (1H, s).

Provenance & Evidence