Electrophilic Tropylation of Aminopyridines and 4-Aminoquinoline

The reactions of 2-, 3-, 4-aminopyridines or 4-aminoquinoline with hydrolytically stable tropylium salts (perchlorate or tetrafluoroborate) have afforded N-(1′-cyclohepta-2′,4′,6′-trienyl)-2-aminopyridine, N-(1′-cyclohepta-2′,4′,6′-trienyl)-3-aminopyridine, N-(1′-cyclohepta-2′,4′, 6′-trienyl)-4-aminopyridine, and N-(1′-cyclohepta-2′,4′,6′-trienyl)-4-aminoquinoline. The effect of imidazole and the tropylium salt anion on the yield and stability of the final reaction products has been studied.