合成路线1

Oxidation of the (-)-Corey's lactone (XIV) with Collins reagent (CrO3 and pyridine) gives aldehyde (XV), which is condensed with phosphonate (IV) by means of thallium ethoxide in benzene to yield the unsaturated difluoroketolactone (XVI). Hydrogenation of compound (XVI) with H2 over Pd/C in ethyl acetate affords the saturated analogue (XVII), which is reduced with NaBH4 in methanol/THF to provide the hydroxylactone (XVIII), which is then protected at the hydroxy group with TBDMS-Cl and imidazole to give the silyl ether (XIX). Hydrolysis of the ester group of compound (XIX) in basic medium, followed by reaction with dihydropyran yields the tetrahydropyranyl ether (XX), which is reduced with DIBAL to afford the lactol (XXI). Condensation of lactol (XXI) with 4-(methoxycarbonyl)butyl triphenylphosphonium bromide (XXII) provides the unsaturated methyl ester (XXIII), which is desilylated by means of TBAF in THF to give the diol (XXIV). Finally, hydrolysis of the ester group of compound (XXIV) with NaOH in methanol yields the already described intermediate prostaglandin F2a derivative (X).