Acetic Anhydride → (+)-Prostaglandin A2

Participants

Reaction Steps

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.

Provenance & Evidence