Benzyl chloroformate → 2-Benzyl 1-t-butyl 5-bromo-1H-pyrrole-1,2-dicarboxylate

HRID 1964606Notes

Reaction equation

HRID 1964606 reaction equation
Br[C:2]1[N:3]([C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])[C:4]([Br:7])=[CH:5][CH:6]=1.C([Li])CCC.Cl[C:21]([O:23][CH2:24][C:25]1[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=1)=[O:22].[Cl-].[NH4+]>C(OCC)C>[Br:7][C:4]1[N:3]([C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])[C:2]([C:21]([O:23][CH2:24][C:25]2[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=2)=[O:22])=[CH:6][CH:5]=1

Participants

6

Reactant 4

HCID 10387Benzyl chloroformateHCID 25517Ammonium ChlorideHCID 11099400tert-Butyl 2,5-dibromo-1H-pyrrole-1-carboxylateHCID 178418339Butyllithium

Product 1

HCID 666830832-Benzyl 1-t-butyl 5-bromo-1H-pyrrole-1,2-dicarboxylateYield 68.5%

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent2×

Procedure

t-Butyl 2,5-dibromo-1H-pyrrole-1-carboxylate (10.98 g, 33.8 mmol) synthesized in Example (66a) was dissolved in diethyl ether (135 mL), and cooled to −78° C. n-Butyl lithium (2.77M hexane solution, 12.8 mL, 35.5 mmol) was added dropwise slowly, and stirring was carried out for 1 hour. To the reaction solution, benzyl chloroformate (6.25 mL, 44.0 mmol) was added dropwise slowly, and stirring was carried out for 30 minutes. With the temperature of the reaction solution being gradually raised to room temperature, stirring was carried out for 1 hour. To the reaction solution, were added a saturated aqueous ammonium chloride solution (200 mL) and diethyl ether (300 mL), and the solution was separated. The organic layer was washed with saturated brine, and subsequently dried over sodium sulfate. The solvent was distilled off under reduced pressure, and the resulting residue was purified using silica gel column chromatography (elution solvent: ethyl acetate/hexane=5%-45%) to afford the desired compound (8.80 g, yield 68%) as a reddish brown oil.

Workup

  1. additionwas added dropwise slowly
  2. stirringstirring
  3. waitwas carried out for 30 minutes
  4. stirringstirring
  5. waitwas carried out for 1 hour
  6. customthe solution was separated
  7. washThe organic layer was washed with saturated brine
  8. dry with materialsubsequently dried over sodium sulfate
  9. distillationThe solvent was distilled off under reduced pressure
  10. customthe resulting residue was purified
  11. washsilica gel column chromatography (elution solvent: ethyl acetate/hexane=5%-45%)

Sources & evidence

ORD record
ord-ec97b9001ee84ba7b2b0ef9e8c7dd57e
Source dataset
uspto-grants-2013_04
Patent number
US08415359B2

Reaction notes

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