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

Participants

Reaction Steps

To 2-oxopropanal phenylhydrazone (5.00 g, 30.8 mmol) in acetic acid (60 mL) was added a 40% aqueous solution of glyoxal (5.9 g, 4.6 mL, 30.8 mmol) and the mixture was heated at reflux for 45 minutes. The acetic acid was removed under reduced pressure. The resultant mixture was diluted with ethyl acetate (100 mL), washed with NaHCO3 and sat. aq. NaCl. Solids were removed by filtration, the filtrate was dried over Na2SO4, filtered and concentrated. The crude material was purified by CombiFlash (180 g column, 0-20 EtOAc/heptane gradient) to afford 1-(4-hydroxy-1-phenyl-1H-pyrazol-3-yl)ethanone as a yellow solid (2.70 g, 43%).

Provenance & Evidence