A short and efficient synthesis of pyrazino-fused tetraazafulvalenes

The tetraazafulvalenes 1 can be easily transformed into pyrazino fused deri vatives of type 3 and 4 via cyclization of both vicinal secondary arylamino functions with chloroacetaldehyde acetals. Similarly, in the course of a c omplex reaction acetals of propionaldehyde, phenylacetaldehyde, propiopheno ne and deoxybenzoin lead to deeply blue colored ring fused products of type 7. This easily feasible annulation reaction is applicable to other heteroc ycles which contain a comparable bis-amidine substructure as examplified fo r 2,3-bis[arylamino]quinoxalines to give the heterocycles 15-17.