Forbindelser, preparater, nevnte forbindelser og preparater for bruk i terapi samt anvendelse av nevnte forbindelser for fremstilling av preparater til medisinsk behandling

Compounds of Formula Iwherein R , R , R and R are as defined in the specification, enantiomers thereof, pharmaceutically acceptable salts thereof, processes for preparing them, pharmaceutical compositions containing them and their use in therapy, especially for treatment of conditions associated with reductions in nicotinic transmission. The compounds of the invention enhance the efficacy of agonists at nicotinic receptors.