Hydrochloric Acid → 1-(4-(1,3,4-oxadiazol-2-yl)phenyl)-3-tert-butyl-1H-pyrazole-5-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A solution of ethyl 1-(4-(1,3,4-oxadiazol-2-yl)phenyl)-3-tert-butyl-1H-pyrazole-5-carboxylate (440 mg, 1.29 mmol) in a mixture comprised of THF (3 mL), methanol (1 mL) and water (1 mL) was cooled to 0° C. and treated with lithium hydroxide (62 mg, 2.59 mmol). The reaction mixture was stirred 3 h at 0° C. and was then allowed to warm to RT over 4 h. Water (15 mL) was added and the mixture was extracted with ether (2×10 mL). The aqueous portion was acidified by addition of 1 M aq HCl (2.5 mL, 2.5 mmol) and was extracted with EtOAc (3×20 mL). The organics were dried (Na2SO4) and concentrated in vacuo to provide 1-(4-(1,3,4-oxadiazol-2-yl)phenyl)-3-tert-butyl-1H-pyrazole-5-carboxylic acid (355 mg, 88% yield). 1H NMR (400 MHz, DMSO-d6): δ 13.35 (br s, 1 H), 9.40 (d, J=3.4 Hz, 1 H), 8.11 (m, 2 H), 7.69 (m, 2 H), 7.01 (d, J=3.2 Hz, 1 H), 1.32 (s, 9 H); MS (ESI) m/z: 313.0 (M+H+).

Provenance & Evidence