Acetic Anhydride → (+)-Prostaglandin A2

HRID 1834053Notes

Reaction equation

HRID 1834053 reaction equation
[CH3:1][CH2:2][CH2:3][CH2:4][CH2:5][C@H:6]([OH:25])/[CH:7]=[CH:8]/[C@@H:9]1[C@@H:14]([CH2:15]/[CH:16]=[CH:17]\[CH2:18][CH2:19][CH2:20][C:21]([OH:23])=[O:22])[C:12](=[O:13])[CH2:11][C@H:10]1O.C(OC(=O)C)(=O)C.C(OCC)(=O)C.CCCCCC.S(=O)(=O)(O)[O-].[K+]>N1C=CC=CC=1.O.CCOCC.CO>[CH3:1][CH2:2][CH2:3][CH2:4][CH2:5][C@H:6]([OH:25])/[CH:7]=[CH:8]/[C@@H:9]1[C@@H:14]([CH2:15]/[CH:16]=[CH:17]\[CH2:18][CH2:19][CH2:20][C:21]([OH:23])=[O:22])[C:12](=[O:13])[CH:11]=[CH:10]1

Participants

9

Reactant 4

HCID 7918Acetic AnhydrideHCID 516920Potassium bisulfateHCID 5280360Prostaglandin E2HCID 21226206Ethyl acetate hexane

Product 1

HCID 5280880(+)-Prostaglandin A2

Reagents, catalysts & solvents 4

HCID 887MethanolSolventHCID 962WaterSolventHCID 1049PyridineSolventHCID 3283Diethyl EtherSolvent

Procedure

To a solution of PGE2, 1,15-lactone (350 mg) in 10 ml of dry pyridine was added 4 ml of acetic anhydride. The solution was allowed to stand at 25° for 3 hours. TLC analysis (25% ethyl acetate/hexane) showed no starting material, only a single, less polar spot. The reaction mixture was cooled in an ice bath and treated dropwise over 15 min. with 20 ml of methanol. The temperature was allowed to rise to 25° over about 2 hours. After an additional 18 hrs. at 25° , the reaction mixture of ice, ether, water, and 70 ml of 2N aqueous potassium bisulfate and extracted thoroughly with ether. The combined extracts were washed with water, aqueous sodium bicarbonate and brine, dried over anhydrous sodium sulfate and concentrated in vacuo to afford PGA2, 1,15-lactone as a residue.

Workup

  1. temperatureThe reaction mixture was cooled in an ice bath
  2. waitto rise to 25° over about 2 hours
  3. waitAfter an additional 18 hrs
  4. extractionextracted thoroughly with ether
  5. washThe combined extracts were washed with water, aqueous sodium bicarbonate and brine
  6. dry with materialdried over anhydrous sodium sulfate
  7. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-0487f50337b648e89bf87f1012414d0d
Source dataset
uspto-grants-1978_01
Patent number
US04067991

Reaction notes

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