Trityl chloride → 4-Bromo-1-trityl-1H-pyrazole

HRID 2426992Notes

Reaction equation

HRID 2426992 reaction equation
[Br:1][C:2]1[CH:3]=[N:4][NH:5][CH:6]=1.[H-].[Na+].[C:9](Cl)([C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1)([C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1)[C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=1>O1CCCC1.C(OCC)(=O)C>[Br:1][C:2]1[CH:3]=[N:4][N:5]([C:9]([C:10]2[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=2)([C:22]2[CH:23]=[CH:24][CH:25]=[CH:26][CH:27]=2)[C:16]2[CH:17]=[CH:18][CH:19]=[CH:20][CH:21]=2)[CH:6]=1

Participants

6

Reactant 3

HCID 6456Trityl chlorideHCID 163754-BromopyrazoleHCID 24758Sodium hydride

Product 1

HCID 108341884-Bromo-1-trityl-1H-pyrazoleYield 94.4%

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolventHCID 8857Ethyl AcetateSolvent

Procedure

A suspension of 4-bromo-1H-pyrazole (10 g) in tetrahydrofuran (230 ml) was stirred for 1 hr at room temperature. While argon gas was provided, sodium hydride was slowly added at 0° C. to the suspension, followed by stirring for 30 min and then for an additional 30 min at room temperature. Then, trityl chloride (22.8 g) was slowly added at 0° C. to the suspension with stirring for 20 min. Further stirring was conducted for 3 hrs at room temperature before the reaction was terminated. Following the removal of excess sodium hydride with distilled water (3 ml) from the reaction at 0° C., the tetrahydrofuran solvent was evaporated in a vacuum and the concentrate thus obtained was diluted in ethyl acetate (200 ml) and washed with distilled water (200 ml) and then with brine (200 ml). The resulting organic layer was dried over anhydrous magnesium sulfate and concentrated by evaporation in vacuo. The residue was diluted in methylene chloride (2 ml) and recrystallized in methanol (200 ml) to give 4-bromo-1-trityl-1H-pyrazole (25 g).

Workup

  1. customWhile argon gas was provided
  2. stirringby stirring for 30 min
  3. waitfor an additional 30 min at room temperature
  4. stirringwith stirring for 20 min
  5. stirringFurther stirring
  6. waitwas conducted for 3 hrs at room temperature before the reaction
  7. customwas terminated
  8. customthe removal of excess sodium hydride with distilled water (3 ml)
  9. customfrom the reaction at 0° C.
  10. customthe tetrahydrofuran solvent was evaporated in a vacuum
  11. concentrationthe concentrate thus
  12. customobtained
  13. washwashed with distilled water (200 ml)
  14. dry with materialThe resulting organic layer was dried over anhydrous magnesium sulfate
  15. concentrationconcentrated by evaporation in vacuo
  16. additionThe residue was diluted in methylene chloride (2 ml)
  17. customrecrystallized in methanol (200 ml)

Sources & evidence

ORD record
ord-0dd8d863894f499e8f7e8e0427377064
Source dataset
uspto-grants-2011_06
Patent number
US07968579B2

Reaction notes

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