L-Pyroglutamic Acid → tert-Butyl 5-oxo-L-prolinate

HRID 907481Notes

Reaction equation

HRID 907481 reaction equation
Cl(O)(=O)(=O)=O.[NH:6]1[C:10](=[O:11])[CH2:9][CH2:8][C@H:7]1[C:12]([OH:14])=[O:13].C(OC[CH2:20][CH2:21][CH3:22])(=O)C.[C:23](=O)([O-])[O-].[Na+].[Na+]>C(Cl)(Cl)(Cl)Cl.CCOCC>[NH:6]1[C:10](=[O:11])[CH2:9][CH2:8][C@H:7]1[C:12]([O:14][C:21]([CH3:20])([CH3:22])[CH3:23])=[O:13]

Participants

7

Reactant 4

HCID 7405L-Pyroglutamic AcidHCID 10340Sodium CarbonateHCID 24247Perchloric AcidHCID 31272Butyl Acetate

Product 1

HCID 10888648tert-Butyl 5-oxo-L-prolinateYield 57.5%

Reagents, catalysts & solvents 2

HCID 3283Diethyl EtherSolventHCID 5943Carbon TetrachlorideSolvent

Procedure

Perchloric acid (70% aqueous, 0.521 cm3, 6.05 mmol) was added dropwise to a stirred suspension of (S)-pyroglutamic acid 9 (1 g, 7.75 mmol) in tent-butyl acetate (12 cm3, 85.5 mmol). The mixture was stirred for 24 h then sodium carbonate (0.80 g, 7.60 mmol) was added cautiously, ether was added and the organic phase washed with saturated sodium hydrogen carbonate solution and brine. The aqueous phase was extracted with ethyl acetate, dried (MgSO4), filtered and the solvent removed to yield an oil to which was added carbon tetrachloride and the solvent evaporated in vacuo to remove traces of acetic acid to give ester 10 (0.81 g, 56%) as a white solid: δH (300 MHz; CDCl3; Me4Si) 1.48 [9H, s, C(CH3)], 2.33-2.45 (4H, m, 3-H2, 4-H2), 4.12-4.16 (1H, m, 5-H) and 6.16 (1H, br s, N—H); δC (75 MHz; CDCl3) 24.7 (CH2, 4-C), 27.8 [CH3, C(CH3)], 29.2 (CH2, 3-C), 55.9 (CH, 5-C), 82.3 [quat., C(CH3)], 170.9 (quat., 5-CO) and 177.7 (quat., 2-C).

Workup

  1. washthe organic phase washed with saturated sodium hydrogen carbonate solution and brine
  2. extractionThe aqueous phase was extracted with ethyl acetate
  3. dry with materialdried (MgSO4)
  4. filtrationfiltered
  5. customthe solvent removed
  6. customto yield an oil to which
  7. customthe solvent evaporated in vacuo
  8. customto remove traces of acetic acid

Sources & evidence

ORD record
ord-e7c5070c96ae4f21ace4eef1d5d1b837
Source dataset
uspto-grants-2011_09
Patent number
US08013170B2

Reaction notes

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