5epsilon-lodo-9-deoxy-6epsilon,9alpha-epoxy-PGF1alpha (I) is protected with tert-butyldimethylsilyl chloride in DMF containing imidazole yielding the disilylated compound (II), which is treated with diazabicyclononane (DBN) in DMF to give the hydroxy keto ester (III). Acetylation of (III) with acetic anhydride in pyridine affords the corresponding acetoxy compound (IV), which by hydrolysis with NaOH affords the free hydroxy acid (V). Oxidation of (V) with Jones' reagent yields the diketonic acid (VI), which by cyclization with aniline (A) in pyridine - methanol followed by esterification with diazomethane is converted into the protected ester (VII). Elimination of the silyl groups of (VII) with tetrabutylanimonium fluoride in THF gives the methyl ester of U-60,257 (VIII), which is finally hydrolyzed with NaOH in methanol.

5epsilon-lodo-9-deoxy-6epsilon,9alpha-epoxy-PGF1alpha (I) is protected with tert-butyldimethylsilyl chloride in DMF containing imidazole yielding the disilylated compound (II), which is treated with diazabicyclononane (DBN) in DMF to give the hydroxy keto ester (III). Acetylation of (III) with acetic anhydride in pyridine affords the corresponding acetoxy compound (IV), which by hydrolysis with NaOH affords the free hydroxy acid (V). Oxidation of (V) with Jones' reagent yields the diketonic acid (VI), which by cyclization with aniline (A) in pyridine - methanol followed by esterification with diazomethane is converted into the protected ester (VII). Elimination of the silyl groups of (VII) with tetrabutylanimonium fluoride in THF gives the methyl ester of U-60,257 (VIII), which is finally hydrolyzed with NaOH in methanol.