Isopropyl iodide → ethyl 1-isopropyl-3-(thiophen-2-yl)-1H-pyrazole-5-carboxylate

HRID 1930337Notes

Reaction equation

HRID 1930337 reaction equation
[CH3:1][C:2](C)([O-])[CH3:3].[K+].[S:7]1[CH:11]=[CH:10][CH:9]=[C:8]1[C:12]1[CH:16]=[C:15]([C:17]([O:19][CH2:20][CH3:21])=[O:18])[NH:14][N:13]=1.IC(C)C.[NH4+].[Cl-]>CS(C)=O>[CH:2]([N:14]1[C:15]([C:17]([O:19][CH2:20][CH3:21])=[O:18])=[CH:16][C:12]([C:8]2[S:7][CH:11]=[CH:10][CH:9]=2)=[N:13]1)([CH3:3])[CH3:1]

Participants

6

Reactant 4

HCID 6362Isopropyl iodideHCID 25517Ammonium ChlorideHCID 23665647Potassium tert-butoxideHCID 178468642HCID 178468642, compound

Product 1

HCID 59826475ethyl 1-isopropyl-3-(thiophen-2-yl)-1H-pyrazole-5-carboxylateYield 73%

Reagents, catalysts & solvents 1

HCID 679Dimethyl SulfoxideSolvent

Procedure

Potassium t-butoxide (0.51 g, 4.5 mmol) was dissolved in DMSO (10 mL) and to this solution was added ethyl 3-(thiophen-2-yl)-1H-pyrazole-5-carboxylate (1.01 g, 4.5 mmol) in small portions and stirred under Ar for 15 min. To this solution was added 2-iodopropane (1.2 g, 6.8 mmol) slowly and stirred for 1 h at RT. Sat. NH4Cl solution was added, the product was extracted with EtOAc (2×40 mL). The combined organics were washed with brine, dried (Na2SO4) and concentrated in vacuo. Purification by silica gel chromatography provided ethyl 1-isopropyl-3-(thiophen-2-yl)-1H-pyrazole-5-carboxylate as a pasty mass (0.88 g, 73% yield). 1H NMR (400 MHz, Acetone-d6): δ 7.47 (dd, J=3.2 Hz, 1.2 Hz, 1H), 7.42 (dd, J=4.8 Hz, 1.2 Hz, 1H), 7.12-7.09 (m, 2H), 5.57-5.51 (m, 1H), 4.37 (q, J=7.2 Hz, 2H), 1.50 (d, J=6.8 Hz, 6H), 1.38 (t, J=7.2 Hz, 3H); MS (ESI) m/z: 265.0 (M+H+).

Workup

  1. stirringstirred for 1 h at RT
  2. extractionthe product was extracted with EtOAc (2×40 mL)
  3. washThe combined organics were washed with brine
  4. dry with materialdried (Na2SO4)
  5. concentrationconcentrated in vacuo
  6. customPurification by silica gel chromatography

Sources & evidence

ORD record
ord-3b1caa7e543a4d4dace4ce75ecda61e2
Source dataset
uspto-grants-2012_05
Patent number
US08188113B2

Reaction notes

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