The objective of the present proposal is to synthesize and evaluate prostaglandin analogs related to natural PGF2Alpha as potential luteolytic agents. We plan to synthesize in optically pure from 12-hydroxy-16(S)-fluoro PGF2Alpha, 12-hydroxy-16(R)-fluoro PGF2Alpha, 12-hydroxy-14-fluoro PGF2Alpha, 12-hydroxy-16;16-difluoro PGF2Alpha, 12-hydroxy-16-phenoxy-17,18,19,20-tetranor PGF2Alpha, 12-hydroxy-16(3-chlorophenoxy)-17,18,19,20-tetranor PGF2Alpha, and 12-hydroxy-16[3-(trifluoromethyl)phenoxy]-17,18,19,20-tetranor PGF2Alpha.