Acetone → HCID 53445980, compound

Participants

Reaction Steps

To a vigorously stirred suspension of NaH (60% dispersion in mineral oil, 2.6 g, 65 mmol, 3.32 equiv.) and diethyl carbonate (4.7 mL, 38.83 mmol, 1.99 equiv.) in dry toluene (30 mL) was added drop wise (over a period of 1 h) a solution of the methyl ketone, 1-benzofuran-2-yl-ethanone (1 g, 7.87 mmol) in toluene (5 mL) under reflux. After addition, the mixture was stirred at reflux for 0.5 h. The mixture was cooled to RT and was acidified with glacial acetic acid. After adding cold water, the mixture was extracted 3 times with ethyl acetate. Combined organic extract was washed with water and brine. After drying over MgSO4, solvent was evaporated to furnish the crude βketoester, 3-benzofuran-2-yl-3-oxo-propionic acid ethyl ester. To the crude product was added absolute ethanol (10 mL) and hydrazine hydrate (1.5 mL, excess). The mixture was kept under reflux for 4 h. A solid separated, which was filtered and washed with EtOH. Upon drying, a 1.87 g (48%) of the pyrazolone (VId) was isolated. 1H-NMR (DMSO-d6) δ 12.5 (br s, 1H), 10.1 (br s, 1H), 7.62-7.18 (series of multiplets, 4H), 7.10 (s, 1H), 5.87 (s, 1H). MS: 201(M+H)

Provenance & Evidence