合成路线1

The sylilation of PGE2 methyl ester (I) with hexamethyldisylazane trimethylchlorosylane (A) gives the bis(trimethylsilyl) ether (II), which by reaction with N-methylphenylsulfonimidoylmethyl magnesium chloride in THF followed by a reductive elimination with Al-Hg affords 9-deoxy-9-methylene-PGE2 methyl ester (III) or its his trimethylsilyl ether (IV) depending on the reaction conditions. The selective hydroboration of (IV) with 9-borabicyclo[3.3.1]nonane (B) in THF yields 9-deoxy-9alpha-hydroxymethyl-PGE2 methyl ester (V), which by mesylation with methanesulfonyl chloride and triethylamine in methylene chloride gives the corresponding mesylate (VI). The treatment ot (VI) with 85% phosphoric acid in THF water eliminates the trimethylsilyl groups yielding 9-deoxy-9alpha-mesyloxymethyl-PGE2alpha methyl ester (VII), which is finally cyclized by treatment with NaOH in MeOH - H2O.