Synthesis of the key component for preparation of 6-keto-prostaglandins by a two-component coupling process: Synthesis of 6-keto-prostaglandin E(1), ornoprostil and Delta(2)-trans-6-keto-prostaglandin E(1)

Starting with commercially available (3S,4R)-3-(methoxymethyloxy)-2-methylidene-4- siloxycyclopentanone-2, useful 6-keto-prostaglandin intermediates 1 have been prepared in good yields by a sequence of reactions which includes treatment with NaBr in the presence of BF3 . OEt(2), Pd-catalysed coupling of the resulting 2-bromomethyl-4-siloxycyclopent-2-enone 3 with the alkenylborane 4 or 9 and conversion of the alkenyl moiety into an epoxy and then into a keto group. The synthesis of 6-keto-PGE(1), ornoprostil and Delta(2)-trans-6-keto-PGE(1) by using 1 is also described.