Synthesis and biological activity of 9-deoxo-9-methylene and related prostaglandins.

A number of PGE analogs have been synthesized in which the C-9 carbonyl group has been replaced by an exo-methylene group. These chemically stable 9-deoxo-9-methylene-PGEs exhibit biological profiles very similar to their less stable PGE relatives. 9-Deoxo-16,16-dimethyl-9-methylene-PGE2 (7) retains the useful uterine-stimulating potency of 16,16-dimethyl-PGE2 but is approximately 300 times less enteropooling in the rat. In preliminary clinical trials, 7 has shown efficacy for pregnancy termination by the oral and vaginal routes of administration, as well as relative freedom from gastrointestinal side effects.