The 7-azanorbornane nucleus of epibatidine: 7-azabicyclo[2.2.1]heptan-7-ium chloride

Abstract

7-Azabicyclo[2.2.1]heptane (7-azanorbornane) is a bridged heterocyclic nucleus found in epibatidine, the alkaloid isolated from the skin of the tropical poison frog Epipedobates tricolor. Since epibatidine is known as one of the most potent acetylcholine nicotinic receptor agonists, a plethora of literature has been devoted to this alkaloid. However, there are no structural data on the unsubstituted 7-azanorbornane, the parent bicyclic ring of epibatidine and its derivatives. We herein present the structural characterization of the 7-azabicyclo[2.2.1]heptane parent ring as its hydrochloride salt, namely 7-azabicyclo[2.2.1]heptan-7-ium chloride, C 6 H 12 N + ÁCl À . The compete cation is generated by a crystallographic mirror plane with the N atom lying on the mirror, as does the chloride anion. In the crystal, the cations are linked to the anions by N-HÁ Á ÁCl hydrogen bonds, which generate [001] chains.