Dichloromethane → 4-dichloromethyl-1-methyl-5-nitro-1H-pyrazole

HRID 1688086Notes

Reaction equation

HRID 1688086 reaction equation
CC(C)([O-])C.[K+].[CH3:7][N:8]1[C:12]([N+:13]([O-:15])=[O:14])=[CH:11][CH:10]=[N:9]1.[CH2:16]([Cl:18])[Cl:17]>CN(C=O)C>[Cl:17][CH:16]([Cl:18])[C:11]1[CH:10]=[N:9][N:8]([CH3:7])[C:12]=1[N+:13]([O-:15])=[O:14]

Participants

5

Reactant 3

HCID 6344DichloromethaneHCID 1431451-Methyl-5-nitropyrazoleHCID 23665647Potassium tert-butoxide

Product 1

HCID 672648164-dichloromethyl-1-methyl-5-nitro-1H-pyrazoleYield 18%

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent2×

Conditions

Temperature
-78 °C

Procedure

To a solution of potassium tert-butoxide (157 ml, 11.0M in THF) and anhydrous DMF (40 ml) at −78° C. was added a mixture of 1-methyl-5-nitro-1H-pyrazole (5.0 g, 39 mmol) in anhydrous methylene chloride (3.5 mL) and anhydrous DMF (25 mL) via dropwise addition. The reaction was stirred at −78° C. for 30 minutes and quenched by the careful addition of acetic acid (20 mL) in methanol (40 mL). The resulting mixture was allowed to warm to room temperature and poured into ice-water and extracted with ethyl acetate. The organic phase was washed with water and brine and dried over by sodium sulfate. Chromatography on silica gel with hexanes and ethyl acetate (3:1→2:1) gave 1.47 g of 4-dichloromethyl-1-methyl-5-nitro-1H-pyrazole (18%): 1H NMR (300 MHz, CDCl3) δ 7.88 (s, 1H), 6.85 (s, 1H), 4.23 (s, 3H); MS (m/e): 210.2 (M+1).

Workup

  1. additionvia dropwise addition
  2. customquenched by the careful addition of acetic acid (20 mL) in methanol (40 mL)
  3. temperatureto warm to room temperature
  4. additionpoured into ice-water
  5. extractionextracted with ethyl acetate
  6. washThe organic phase was washed with water and brine
  7. dry with materialdried over by sodium sulfate

Sources & evidence

ORD record
ord-346cf3637b844062a6b89ff7b71e3c7a
Source dataset
uspto-grants-2012_04
Patent number
US08148391B2

Reaction notes

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