Syntheses of several stable PGI2 analogs substituted by an electron-withdrawing substituent at C-5 or C-7 are described. Reaction of PGI2 methylester () with benzenesulfenylchloride gave (5E)-5-phenylthio-PGI2 () or (5 R)-5-phenylthio-Δ6-PGI1 () according to the reaction condition employed. Allyl sulfide was transformed into (7 S )-7-hydroxy-PGI2 () and (7 S )-7-acetoxy-PGI2 () via stereocontrolled