A new prostaglandin analog 15(R, S)-dl-ω-ethyl-13, 14-dehydro-prostaglandin F_2α (10) has been synthesized from dl-epoxide 4 via a five-step process.The key reaction step involved in this synthesis was the formation of compound 5 which was prepared from 4 with ethylmethoxy aluminum reagent 3.Molecular oxygen in presence of Pt transformed 5 to the lactone 6.6 was reduced to 7 by diieobutylaluminum hydride.Product 10 was finally obtained from dealkylation of compound 9 which was prepared by means of Wittig reaction.Alternatively activated MnO₂ was used for the oxidation of 5 to give a mixture of the lactone 6 and lactol 7.The mixture can be reduced directly with a,n equivalant amount of diisobutylaluminum hydride to 7.The yield was comparable with that of the O₂/Pt method.Compound 10 exhibits high luteolytic and antifertilitic effects with low smooth muscle spasmogenic activity.Further clinical trials are in progress.