tert-Butanol → tert-butyl 5-nitro-1H-pyrazol-3-ylcarbamate

HRID 1526109Notes

Reaction equation

HRID 1526109 reaction equation
P(N=[N+]=[N-])(=O)(OC1C=CC=CC=1)[O:2]C1C=CC=CC=1.C([N:22]([CH2:25][CH3:26])[CH2:23]C)C.[N+:27]([C:30]1[NH:34][N:33]=C(C(O)=O)C=1)([O-:29])=[O:28].C(=O)([O-])[O-].[K+].[K+].[C:44]([OH:48])([CH3:47])([CH3:46])[CH3:45]>>[N+:27]([C:30]1[NH:34][N:33]=[C:25]([NH:22][C:23](=[O:2])[O:48][C:44]([CH3:47])([CH3:46])[CH3:45])[CH:26]=1)([O-:29])=[O:28]

Participants

6

Reactant 5

HCID 6386tert-ButanolHCID 8471TriethylamineHCID 11430Potassium CarbonateHCID 123414Diphenylphosphoryl azideHCID 862226845-Nitro-1H-pyrazole-3-carboxylic acid

Product 1

HCID 135971896tert-butyl 5-nitro-1H-pyrazol-3-ylcarbamateYield 30.1%

Procedure

39 ml of tert-butanol, 27.44 ml (127.3 mmol) of diphenyl phosphorazidate and 17.7 ml (127.32 mmol) of triethylamine are added respectively to 10 g (63.66 mmol) of 5-nitro-1H-pyrazol-3-carboxylic acid. The solution is carried at reflux for 8 hours and then saturated aqueous potassium carbonate solution is added until pH=8 and the product is extracted several times with ethyl acetate. The organic phases are combined, dried on magnesium sulfate and concentrated. The residue obtained is triturated in methanol to yield 4.38 g (30.1%) of tert-butyl 5-nitro-1H-pyrazol-3-ylcarbamate in the form of a yellow solid. The filtrate is concentrated and purified by silica gel chromatography (eluent: 7:3 cyclohexane/ethyl acetate) to yield an additional 1.49 g (10.3%) of the desired product.

Workup

  1. temperatureat reflux for 8 hours
  2. extractionthe product is extracted several times with ethyl acetate
  3. customdried on magnesium sulfate
  4. concentrationconcentrated
  5. customThe residue obtained
  6. customis triturated in methanol

Sources & evidence

ORD record
ord-a511d4e4df884df08b978a66bfbe6786
Source dataset
uspto-grants-2015_07
Patent number
US09085575B2

Reaction notes

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