Diisopropylamine → 1,3-Dimethyl-5-(tributylstannyl)-1H-pyrazole

HRID 906548Notes

Reaction equation

HRID 906548 reaction equation
[Li+].CC([N-]C(C)C)C.C(NC(C)C)(C)C.[Li]CCCC.[CH3:21][N:22]1[CH:26]=[CH:25][C:24]([CH3:27])=[N:23]1.CN1C(C)=CC=N1.[CH2:35]([Sn:39](Cl)([CH2:44][CH2:45][CH2:46][CH3:47])[CH2:40][CH2:41][CH2:42][CH3:43])[CH2:36][CH2:37][CH3:38]>C1COCC1.O>[CH3:21][N:22]1[C:26]([Sn:39]([CH2:40][CH2:41][CH2:42][CH3:43])([CH2:44][CH2:45][CH2:46][CH3:47])[CH2:35][CH2:36][CH2:37][CH3:38])=[CH:25][C:24]([CH3:27])=[N:23]1

Participants

9

Reactant 6

HCID 7912DiisopropylamineHCID 15096Tributyltin ChlorideHCID 790961H-Pyrazole, 1,3-dimethyl-HCID 1365021,5-DimethylpyrazoleHCID 2724682Lithium diisopropylamideHCID 178418339Butyllithium

Product 1

HCID 591644971,3-Dimethyl-5-(tributylstannyl)-1H-pyrazoleYield 36%

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 8028TetrahydrofuranSolvent2×

Conditions

Temperature
-78 °C

Procedure

To a solution of LDA (prepared from diisopropylamine (3.6 mL, 1.1 equiv) and n-BuLi (1.6M in hexanes, 14.3 mL, 1.1 equiv) in THF (80 mL) at −78° C. was added dropwise a solution containing a 1:1 mixture of 1,3-dimethyl-1H-pyrazole and 1,5-dimethyl-1H-pyrazole (2 g, 1 equiv) in THF (5 mL) with keeping the temperature below −70° C. At the end of the addition, the mixture was stirred for 30 min at −78° C. before addition of tributyltin chloride (6.16 mL, 1.1 equiv) with keeping the temperature below −70° C. The mixture was then stirred at −78° C. for 30 min and at r.t. for 2 h. The mixture was poured into water and then extracted with AcOEt (3 times). The organic phases were combined, dried (Na2SO4) and concentrated in vacuo to give a yellow paste. The crude product was purified by flash chromatography (hexanes to EtOAc/hexanes (40:60)) to yield 1,3-dimethyl-5-tributylstannanyl-1H-pyrazole (2.88 g, 36%) as a colorless syrup. (TLC rf 0.46 in EtOAc/hexanes 20:80).

Workup

  1. additionwas added dropwise a solution
  2. additioncontaining
  3. customthe temperature below −70° C
  4. additionAt the end of the addition
  5. customthe temperature below −70° C
  6. extractionextracted with AcOEt (3 times)
  7. dry with materialdried (Na2SO4)
  8. concentrationconcentrated in vacuo
  9. customto give a yellow paste
  10. customThe crude product was purified by flash chromatography (hexanes to EtOAc/hexanes (40:60))

Sources & evidence

ORD record
ord-ad2ba467ca324638b03f1817c5d3bfff
Source dataset
uspto-grants-2011_09
Patent number
US08012988B2

Reaction notes

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