1,4,7,10-tetraazatetracyclo[5.5.1.04,13.010,13]tridecane: Degenerate rearrangement of its conjugate acid

The highly symmetrical 1,4,7,10-tetraazatetracyclo[5.5.1.0^4,13.0^10,13]tridecane (1) has been synthesized by two methods. The proton NMR spectrum of 1 is analyzed. The cyclic tetraaminomethane derivative undergoes a remarkable series of degenerate prototropic and conformational equilibria. The temperature dependence of the proton NMR spectra of 1 and its conjugate acid 3 are interpreted in terms of a large rate enhancement of intramolecular nucleophilic addition to guanidinium ion 3 (ring-chain tautomerism) compared to its acyclic counterpart.