合成路线1

4) The protection of the bicyclic lactone (XXVIII) with dihydropyran and PPTS in THF gives the bistetrahydropyranyl ether (XXIX), which is reduced with DIBAL in THF to the lactol (XXX). The reaction of (XXX) with bromomagnesium acetylide in THF yields (XXXI), which is selectively benzoylated with benzoyl chloride and pyridine affording the monobenzoyl ester (XXXII). The silylation of the secondary hydroxy group of (XXXII) with TBDMS-Cl and imidazole in THF gives the fully protected compound (XXXIII), which is treated with KOH in methanol in order to eliminate the benzoyl group, yielding the hydroxymethyl derivative (XXXIV). The reaction of (XXXIV) with mesyl chloride and triethylamine in dichloromethane affords the mesylate (XXXV), which is cyclized by means of NaI, AIBN and tributyltin hydride in hot glyme giving the bicyclo[3.3.0]octane (XXXVI). The desilylation of (XXXVI) with TBAF and triethylamine in THF yields compound (XXXVII) with a secondary hydroxy group, which is acetylated with acetic anhydride to the acetate (XXXVIII). The condensation of (XXXVIII) with the copper derivative (XXXIX) affords the silylated pentanol derivative (XL), which is deprotected with TBAF and triethylamine in THF to the free pentanol derivative (XLI). The oxidation of (XLI) with SO3/Pyr in DMSO gives the corresponding aldehyde (XLII), which is further oxidized with Ag2O and NaOH in ethanol, and esterified with diazomethane yielding the methyl ester (XLIII). The deprotection of (XLIII) with PPTS in methanol, followed by selective silylation of the primary alcohol with TBDMS-Cl affords the monosilylated compound (XLIV), which is treated with dihydropyran and PPTS in order to protect the secondary hydroxy group yielding (XLV). The desilylation of (XLV) with TBAF, followed by oxidation of the primary alcohol with SO3/Pyr gives the corresponding aldehyde (XLVI), which is condensed with the previously described phosphonate (XV) by means of NaH in glyme affording the ketonic prostacycline (XLVII). Finally, this compound is deprotected with PPTS in methanol and reduced with diisobutylaluminum 2,6-di-tert-butylphenolate giving a mixture of diastereomers that is separated by column chromatography.