Glyoxal → 1-(1-benzyl-4-hydroxy-1H-pyrazol-3-yl)ethanone

Participants

Reaction Steps

To a 40% aqueous solution of glyoxal (8.28 g, 6.55 mL, 57.1 mmol) was added a slurry of 2-oxopropanal benzylhydrazone (10.1 g, 57.1 mmol) in water (250 mL) and methanol (25 mL). The resulting mixture was heated at reflux for 3 hours before cooling to room temperature. The mixture was extracted with EtOAc (2×100 mL) and the combined organic extracts were washed with water, saturated aqueous NaCl, dried over Na2SO4, filtered and concentrated. The crude material was purified by CombiFlash (120 g column, 0-100% EtOAc/heptane gradient) to provide 1-(1-benzyl-4-hydroxy-1H-pyrazol-3-yl)ethanone (4.07 g, 33%).

Provenance & Evidence