Prostaglandin E2 CAS NO.363-24-6

Hexamethyldisilazane (1 ml) and trimethylchlorosilane (0.2 ml) are added with stirring to a solution of PGA2 (250 mg) in 4 ml of tetrahydrofuran at 0°C under nitrogen. This mixture is maintained at 5°C for 15 hours. The mixture is then evaporated under reduced pressure. Toluene is added and evaporated twice. Then the residue is dissolved in 6 ml of methanol, and the solution is cooled to -20°C. Hydrogen peroxide (0.45 ml; 30% aqueous) is added. Then, 1N sodium hydroxide solution (0.9 ml) is added dropwise with stirring at - 20°C. After 2 hours at -20°C, an additional 0.3 ml of the sodium hydroxide solution is added with stirring at -20°C. After another hour in the range -10°C to -20°C, an additional 0.1 ml of the sodium hydroxide solution is added. Then, 1.5 ml of 1 N hydrochloric acid is added, and the mixture is evaporated under reduced pressure. The residue is extracted with ethyl acetate, and the extract is washed successively with 1 N hydrochloric acid and
ine, dried with anhydrous sodium sulfate and evaporated.

The residue is dissolved in 5 ml of diethyl ether. To this solution is added 0.5 ml of methanol and 0.1 ml of water. Amalgamated aluminum made from 0.5 g of aluminum metal is then added in small portions during 3 hours at 25°C. Then, ethyl acetate and 3 N hydrochloric acid are added, and the ethyl acetate layer is separated and washed successively with 1 N hydrochloric acid and
ine, dried with anhydrous sodium sulfate, and evaporated. The residue is chromatographed on 50 g of acid-washed silica gel, eluting first with 400 ml of a gradient of 50- 100% ethyl acetate in Skellysolve B, and then with 100 ml of 5% methanol in ethyl acetate, collecting 25 ml fractions. Fractions 9 and 10 are combined and evaporated to give 18 mg of 11β-PGE2. Fractions 17-25 are combined and evaporated to give 39 mg of PGE2.