4,5-Bis(dimethylamino)quinolines: Proton Sponge versus Azine Behavior

Two first representatives, 5 and 6, of the still unknown 4,5-bis(dimethylamino)quinoline have been synthesized and studied. While the former, being protonated either at the peri-NMe2 groups or at the ring nitrogen, has been shown to display properties of both a proton sponge and azine, its counterpart 6 behaves exclusively as azine giving only a quinolinium salt.