Hydrochloric Acid → 1-tert-butyl-5-methyl-1H-pyrazole-3-carboxylic acid

HRID 1098592Notes

Reaction equation

[C:1]([N:5]1[C:9]([CH3:10])=[CH:8][C:7]([C:11]([O:13]CC)=[O:12])=[N:6]1)([CH3:4])([CH3:3])[CH3:2].C(O)C.O.O1CCOCC1.[OH-].[Li+].Cl>O>[C:1]([N:5]1[C:9]([CH3:10])=[CH:8][C:7]([C:11]([OH:13])=[O:12])=[N:6]1)([CH3:4])([CH3:2])[CH3:3]

Participants

Conditions

Temperature: 40 °C

Procedure

To a solution of ethyl 1-tert-butyl-5-methyl-1H-pyrazole-3-carboxylate (0.60 g, 2.85 mmol) in a mix of ethanol:water:dioxane (1:1:1, 9 mL) was added lithium hydroxide (0.48 mg, 11.4 mmol). The mixture was stirred at 40° C. for 5 hours. The solution was checked by LC-MS and diluted with water (10 mL) and the pH adjusted to 2 with 1N HCl. The solution was extracted with EtOAc (2×10 mL) and the combined organic phases washed with brine (20 mL), dried (NaSO4), and concentrated in vacuo to obtain 1-tert-butyl-5-methyl-1H-pyrazole-3-carboxylic acid (0.50 g, 96% yield). 1H NMR (400 MHz, DMSO-d6): δ 12.4 (s, 1H), 5.47 (s, 1H), 2.42 (s, 3H), 1.56 (s, 9H); MS (ESI) m/z: 183.1 (M+H+).

Workup

extractionThe solution was extracted with EtOAc (2×10 mL)
washthe combined organic phases washed with brine (20 mL)
dry with materialdried (NaSO4)
concentrationconcentrated in vacuo

Sources & evidence

ORD record: ord-a5f19b82dd9e4ff9a2b99fb154a6dbbf
Source dataset: uspto-grants-2012_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08143293B2

Reaction notes

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