反应详情

To a clean round bottom flask equipped with a stir bar, Dean-Stark trap, and reflux condenser was added 3-isopropyl-1H-pyrazole-5-carboxylic acid (1 gram, 6.49 mmol, purchased from Fisher Scientific). 30 mL of ethanol (95%, purchased from Fisher Scientific) was added followed by 30 mL of benzene. 43 μL of acetyl chloride was then added and the solution refluxed over the three days. The solvent was then removed using a Buchi rotoevaporator. The residue was then taken up in ethyl acetate and washed with NaHCO3 (saturated). It was then dried with sodium sulfate, filtered and concentrated. Purification using a Teledyne ISCO silica chromatography (hexanes/ethyl acetate gradient) afforded the desired ester. Yield, 85% 1H-NMR δ 6.7 (s, 1H), 5.1 (bs, NH), 4.41 (q, 2H), 3.13 (septet, 1H), 1.38 (t, 3H), 1.33 (d, 6H).

1. customTo a clean round bottom flask equipped with a stir bar
2. temperatureDean-Stark trap, and reflux condenser
3. temperaturethe solution refluxed over the three days
4. customThe solvent was then removed
5. washwashed with NaHCO3 (saturated)
6. dry with materialIt was then dried with sodium sulfate
7. filtrationfiltered
8. concentrationconcentrated
9. customPurification