Process for the Preparation of Prostaglandin Analogues

A process for preparing a prostaglandin analogue of formula (11)

• wherein
• R1 represents H, C1-C5-alkyl, or benzyl;
• X represents CH2, O, or S;
• Z represents O or NH;
• and
• R′ represents C2-C4-alkyl;
• phenyl optionally substituted by halogen, C1-C5-alkyl, C1-C4-alkoxy, CF3, C2-C4-polyhaloalkyl, or C1-C3-aliphatic acylamino;
• 5- or 6-membered heterocycle containing one or more hetero atoms selected from a group consisting of nitrogen, oxygen and sulfur;
• C3-C7-cycloalkyl;
• or C3-C7-cycloalkenyl;
• the process comprise a step of converting a compound of formula (8′):
• to the compound of formula (11), wherein R3 represents hydrogen or a hydroxyl protecting group.