Enantiospecific activity of tetracyclic PAF-antagonists

The syntheses of two enantiomeric tetracyclic compounds, the thieno3,2-f]pyrrolo2,1-c]1,2,4]triazolo4,3-a]1,4]diazepines 10a and 10b are described. Testing of these enantiomers as inhibitors of platelet activating factor (PAF) revealed good enantiospecificity, meaning that one enantiomer is responsible for the observed biological activity.