Cognition-activating properties of 3-(Aryloxy)pyridines.

A series of 3-(aryloxy)pyridines was found to possess activity in enhancing retention for passive avoidance learning in mice. This test was used to select compounds with potential therapeutic properties for the treatment of cognitive disorders. Reference drugs that gave positive results in this procedure included d-amphetamine, magnesium pemoline, methyl phenidate, picrotoxin, phenytoin, and ethosuximide. All active compounds gave inverted U-shaped dose-response curves. The most active compounds of the 3-(aryloxy)pyridines included 3-phenoxypyridine (1), 3-(2-fluorophenoxy)pyridine (2), 3-(4-fluorophenoxy)pyridine (4), 3,3'-oxybis(pyridine) (23), and 3,3'-oxybis(pyridine) 1-oxide (24). 3-Phenoxypyridine (1) was clearly superior to all of the analogues tested in terms of the level of retention, grammometric potency, and the breadth of its inverted U-shaped dose-response curve. It was given the designation of CI-844 and after a detailed study of its pharmacological profile was submitted for preclinical toxicology.