In the development of new prostaglandin analogues, the most beneficial modifications for obtaining prostaglandin (PG) analogs with different biological activities have been done in the w-side chain. This chain is introduced, in the well known total stereo-controlled Corey convergent synthesis of PGs, by using a key β-ketophosphonate in an E-HEW-stereoselective olefination with an aldehyde linked to a key cyclopentane intermediate. The concept of PG w-side chain is design in the β-ketophosphonate intermediate. In vivo, the PGs are inactivated by enzyme oxidation of the 15-α-OH group to 15-keto group. By using 15-, 16- substituents or 16-aryloxy substituents, the inactivation was diminished. In this direction, we intend to diminish inactivation by introducing bulky bicyclo[3.3.0]octane or bicyclo[3.3.0]oct-6-ene substituents linked to the C-15 carbon atom. For this goal we synthesize the key β-ketophosphonate intermediates starting from bicyclo[3.3.0]oct(a)ene acids by a two or three step sequence. Two mono-acid β-ketophosphonates, one ester β-ketophosphonate and a bis-β-ketophosphonate compounds were obtained. The ester β-ketophosphonate was used to build the w-side chain of the concepted PG analog. The bis-β-ketophosphonate will create a pseudo PG compound with two PG fragments linked to a bicyclo[3.3.0]octane fragment. The compounds were characterized by elemental analysis, IR and high resolution ¹H- and ¹³C-NMR spectroscopy.