L-Pyroglutamic Acid → Methyl 5-oxo-L-prolinate

HRID 2415049Notes

Reaction equation

HRID 2415049 reaction equation
[NH:1]1[C:5](=[O:6])[CH2:4][CH2:3][C@H:2]1[C:7]([OH:9])=[O:8].S(Cl)(Cl)=O.[C:14](=O)(O)[O-].[Na+]>CO>[CH3:14][O:8][C:7](=[O:9])[C@@H:2]1[CH2:3][CH2:4][C:5](=[O:6])[NH:1]1

Participants

5

Reactant 3

HCID 7405L-Pyroglutamic AcidHCID 24386Thionyl ChlorideHCID 516892Sodium Bicarbonate

Product 1

HCID 78646Methyl 5-oxo-L-prolinateYield 80%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

To a solution of L-pyroglutamic acid (32.7 g, 0.253 mol) in methanol (600 mL) was added thionyl chloride (2.40 mL, 32.9 mmol), and the resulting solution was stirred at room temperature for 16 h. The reaction mixture was neutralized to pH=7 with saturated aqueous sodium bicarbonate and concentrated in vacuo. The residue was dissolved in methylene chloride, washed with brine, dried over magnesium sulfate, and concentrated. The residue was distilled under high vacuum to give the product as a colorless oil (28.9 g, 80%), b.p. 118-126° C./0.35 mm Hg. 1H NMR (300 MHz, CDCl3): δ 2.36 (m, 4 H), 3.77 (s, 3 H), 4.27 (dd, 1 H, J=5.0, 8.4), 6.78 (s, 1 H).

Workup

  1. concentrationconcentrated in vacuo
  2. dissolutionThe residue was dissolved in methylene chloride
  3. washwashed with brine
  4. dry with materialdried over magnesium sulfate
  5. concentrationconcentrated
  6. distillationThe residue was distilled under high vacuum

Sources & evidence

ORD record
ord-a6613dbb06714805bbdc8d361b4cae2e
Source dataset
uspto-grants-2004_11
Patent number
US06818643B1

Reaction notes

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