EMD-33.290 can be prepared by conjugate addition of 2-hydroxy-2-methylheptanethiol (II) to 3-hydroxy-5-oxocyclopentenylheptanoic acid p-benzamidophenyl ester (I) to give rise to the title compound as the main product (III) along with two epimers. Isolation of pure EMD-33.290 can be achieved by medium-pressure chromatography. An alternative synthesis utilizing the Roberts' approach has been reported to give the appropriate PGF2alpha analogue, which is converted to EMD-33.290 by selective oxidation.