合成路线1

A new synthesis of rosaprostol has been developed: Reaction of 3-(dimethoxyphosphorylmethyl)-2-cyclopenten-1-one (I) with 7-iodoheptanoic acid methyl ester (II) by means of NaH in DMSO gives the C-2 alkylated cyclopentenone (III), which is condensed with pentanal (IV) by means of NaOMe in methanol to yield the dienone (V). Reduction of the double bonds of (V) with H2 over PtO2 in acetic acid affords a mixture of the cis- and trans-cyclopentanones (VI) and (VII) which, without isolation, is submitted to epimerization with TsOH in methanol to furnish almost quantitatively the desired trans-isomer (VII). The hydrolysis of the methyl ester of (VII) with NaOH in dioxane/water gives the corresponding carboxylic acid (VIII), which is finally hydrogenated with NaBH4 in methanol.