Pyrrolidone carboxylic acid → Methyl 5-oxo-DL-prolinate

HRID 747907

Reaction equation

HRID 747907 reaction equation
[NH:1]1[C:5](=[O:6])[CH2:4][CH2:3][CH:2]1[C:7]([OH:9])=[O:8].[CH3:10]O.OS(O)(=O)=O.[OH-].[Na+]>C1(C)C=CC=CC=1>[CH3:10][O:8][C:7]([CH:2]1[CH2:3][CH2:4][C:5](=[O:6])[NH:1]1)=[O:9]

Participants

6

Reactant 4

HCID 499Pyrrolidone carboxylic acidHCID 887MethanolHCID 1118Sulfuric Acid2×HCID 14798Sodium Hydroxide

Product 1

HCID 500249Methyl 5-oxo-DL-prolinate

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

To a solution of DL-pyroglutamic acid (50 g, 0.387 mol) in 157 mL CH3OH (3.87 mol) and 100 mL toluene was added concentrated H2SO4 (2.5 mL). This mixture was warmed to reflux and allowed to stir for 16 h. Since starting material remained, another 4 mL concentrated H2SO4 was added and the mixture stirred at reflux for an additional 24 h then was cooled to ambient temperature and 20% aqueous NaOH was added to bring the solution to pH ˜6. The mixture was concentrated under reduced pressure and the residue was dissolved in CH2Cl2, filtered through Celite® diatomaceous earth, concentrated and purified via Kugelrohr distillation. The resulting material was carried on directly to the next reaction.

Workup

  1. temperatureThis mixture was warmed
  2. temperatureto reflux
  3. stirringthe mixture stirred
  4. temperatureat reflux for an additional 24 h
  5. concentrationThe mixture was concentrated under reduced pressure
  6. dissolutionthe residue was dissolved in CH2Cl2
  7. filtrationfiltered through Celite® diatomaceous earth
  8. concentrationconcentrated
  9. distillationpurified via Kugelrohr distillation
  10. customdirectly to the next reaction

Sources & evidence

ORD record
ord-ac67cffa5d134231b69fb596799363c4
Source dataset
uspto-grants-2008_07
Patent number
US07399765B2

Linked notes

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