Dyotropic Rearrangements of Tetraazafulvalenes - A New Approach to Aminosubstituted 1,4,5,8Tetraazanaphthalenes

Tetraazafulvalenes 1 rearrange in the presence of Montmorillonite-clay to give strongly fluorescent 1,4,5,8tetraazanaphthalenes of type 2. This observation agrees with that reported for the cross-conjugated systeme of indigo, thus indicating a dyotropic rearrangement has taken place. Inclusion of the extended (pi)-electron-systeme of 1 should facilitate this symmetry forbidden [(sigma)2+(sigma)2]-process. Based on these results, some reactions of heterofulvalenes and -fulvenes reported in the literature can now be explained by dyotropic rearrangements. The easy rearrangement of 1 in the presence of K10 and DMF opens the way for the synthesis of hard to obtain ring-fused pyrazines of type 2.