Potassium Carbonate → tert-Butyl 4-(2-fluoroethyl)piperazine-1-carboxylate

HRID 1785125Notes

Reaction equation

HRID 1785125 reaction equation
C(=O)([O-])[O-].[K+].[K+].Br[CH2:8][CH2:9][F:10].[C:11]([O:15][C:16]([N:18]1[CH2:23][CH2:22][NH:21][CH2:20][CH2:19]1)=[O:17])([CH3:14])([CH3:13])[CH3:12]>C(#N)C>[C:11]([O:15][C:16]([N:18]1[CH2:23][CH2:22][N:21]([CH2:8][CH2:9][F:10])[CH2:20][CH2:19]1)=[O:17])([CH3:14])([CH3:12])[CH3:13]

Participants

5

Reactant 3

HCID 11430Potassium CarbonateHCID 129822-Fluoroethyl bromide2×HCID 143452tert-Butyl piperazine-1-carboxylate

Product 1

HCID 21082715tert-Butyl 4-(2-fluoroethyl)piperazine-1-carboxylateYield 57%

Reagents, catalysts & solvents 1

HCID 6342AcetonitrileSolvent

Procedure

Potassium carbonate (1.85 g, 13.4 mmol) and 1-bromo-2-fluoroethane (440 μl, 5.9 mmol) were added to a solution of tert-butyl-1-piperazinecarboxylate (1 g, 5.4 mmol) in acetonitrile (12 ml). The reaction mixture was stirred at 65?C for 3.5 hours after which time more 1-bromo-2-fluoroethane (160 μl, 2.1 mmol) was added. The reaction was heated for a further 3 hours then filtered to remove the inorganic solids. The filtrate was concentrated and the crude product was purified using column chromatography eluting with ethyl acetate to give 4-(2-fluoroethyl)-piperazine-1-carboxylic acid tert-butyl ester (714 mg, 57%). NMR Spectrum: (CDCl3) 1.46 (s, 9H); 2.50 (t, 4H); 2.70 (dt, 2H); 3.45 (t, 4H); 3.45 (t, 4H); 4.57 (dt, 2H) MS-ESI: 233 [MH]+

Workup

  1. additionwas added
  2. temperatureThe reaction was heated for a further 3 hours
  3. filtrationthen filtered
  4. customto remove the inorganic solids
  5. concentrationThe filtrate was concentrated
  6. customthe crude product was purified
  7. washeluting with ethyl acetate

Sources & evidence

ORD record
ord-3c9b87ce15c1466892dafb25794e12aa
Source dataset
uspto-grants-2009_03
Patent number
US07504408B2

Reaction notes

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