Tetrabutylammonium Fluoride → tert-butyl 4-ethynyl-1H-pyrazole-1-carboxylate

HRID 2205852Notes

Reaction equation

HRID 2205852 reaction equation
C[Si]([C:5]#[C:6][C:7]1[CH:8]=[N:9][N:10]([C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13])[CH:11]=1)(C)C.[F-].C([N+](CCCC)(CCCC)CCCC)CCC>C1COCC1>[C:6]([C:7]1[CH:8]=[N:9][N:10]([C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13])[CH:11]=1)#[CH:5]

Participants

4

Reactant 2

HCID 2724141Tetrabutylammonium FluorideHCID 68478797tert-butyl 4-((trimethylsilyl)ethynyl)-1H-pyrazole-1-carboxylate

Product 1

HCID 45382264tert-butyl 4-ethynyl-1H-pyrazole-1-carboxylateYield 62.5%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Conditions

Temperature
2.5 °C

Procedure

tert-Butyl 4-((trimethylsilyl)ethynyl)-1H-pyrazole-1-carboxylate (3) (3.88 g 14.69 mmole) was dissolved in THF (40 mL) and cooled to 0-5° C. A 1M solution of tetra-n-butylammonium fluoride in THF (16 mL, 16 mmole) was added and the reaction was stirred for 20 minutes. The THF was evaporated and the residue was taken up in ethyl acetate (50 mL) and washed with water (×2) and with brine, then dried and evaporated. The residue was purified on a flash column (silica, eluting with 15% ethyl acetate in cyclohexane) to give the title compound (1.765 g, 62%). 1H-NMR (CDCl3, 500 MHz): δ 1.68 (s, 9H, 3.11 (s, 1H), 7.79 (s, 1H), 8.24 (s, 1H).

Workup

  1. customThe THF was evaporated
  2. washwashed with water (×2) and with brine
  3. customdried
  4. customevaporated
  5. customThe residue was purified on a flash column (silica, eluting with 15% ethyl acetate in cyclohexane)

Sources & evidence

ORD record
ord-6ac5a62d113843fd8ac31808ffce4cfe
Source dataset
uspto-grants-2016_06
Patent number
US09371319B2

Reaction notes

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