Synthesis and gastric antisecretory properties of alpha chain diene derivatives of misoprostol.

The synthesis and gastric antisecretory activity in dogs of seven alpha chain diene derivatives of misoprostol are described. The key intermediates in the preparation of these compounds were C-9 tert-butyldimethylsilyl enol ethers that were obtained by in situ silylation of cuprate enolates derived from alpha chain unsaturated cyclopentenones. Selenylation chemistry on these intermediates provided the C2-C3 trans dienes that, where possible, were also deconjugated to produce the corresponding C3-C4 dienes. The most interesting structure in this series is the C5-C6 cis, C3-C4 cis/trans (1:1) diene that could not be readily separated chromatographically into its individual geometric isomers. The gastric antisecretory activity of the mixture of isomers was approximately 3 times greater than that of misoprostol by intragastric administration. The separation of undesired diarrheogenic effects from antisecretory activity was significantly improved relative to misoprostol.