Synthesis of (+)-11-deoxy-15-ethynyl prostaglandins

This article describes the preparation of (+)-11-deoxy-15-ethynyl prostaglandins (1 & 16). The key step involves a conjugate addition of the substituted 1-lithio-1-oct-1-ene (2) to the cyclopentenone (3 & 12) to furnish 11-deoxy-prostaglandin skeleton in a simple fashion. Of particular interest in this synthesis is the preparation of alkyl side chain (7) which was achieved in an efficient three-step synthesis starting from the readily available beta-iodo vinyl ketone (4).