Hydrochloric Acid → HCID 4542029, compound

Participants

Reaction Conditions

Reaction Steps

5-Cyclopentyl-1H-pyrazol-3-carboxylic acid ethyl ester (17.1 g, 82 mmol) and 1M NaOH solution (205 ml, 205 mmol) were dissolved in 1,4-dioxan (300 ml) and the reaction was heated to 50° C. under nitrogen and stirred for 3 hours. The reaction mixture was cooled, adjusted to pH 2 using concentrated hydrochloric acid and the solvent was removed under reduced pressure. The residual solid was azeotrped with toluene (2×30 ml), dissolved in ethyl acetate (500 ml) and washed with water (200 ml). The aqueous phase was removed, extracted with ethyl acetate (2×200 ml) and the combined organic extracts were dried over MgSO4. The solvent was removed under reduced pressure and the residue was azeotrped with dichloromethane (2×50 ml) to give 5-cyclopentyl-1H-pyrazol-3-carboxylic acid (13 g) as a white solid. 1H NMR (400 MHz, DMSO-D6): δ=12.75-12.88 (2H, brs), 6.43 (1H, s), 2.97-3.08 (1H, quin), 1.91-2.02 (2H, m), 1.50-1.76 (6H, 2×m) ppm. LRMS (electrospray): m/z [M−H]+ 179. Anal. Found C, 59.72; H, 6.74; N, 15.37. C9H12N2 requires C, 59.99; H, 6.71; N, 15.55%.

Provenance & Evidence