2,3-diazaporphyrins bearing two nitrogen atoms at the periphery

The first synthesis of 2,3-diazaporphyrins 3 bearing two nitrogen atoms at peripheral positions from tripyrranes 1, prepared in situ by mild acidolysi s and decarboxylation of the di-t-butyldicarboxylates, and 4H-1,2,4-triazol -3,5-dicarbaldehyde (2) is described, using the [3+1] principle of porphyri ne cyclization. Similar to the parent porphyrins, the new diazaporphyrins 3 exhibit significantly shielded inner protons, reflecting the ring current of an 18 pi aromatic system and Soret bands in the UV-vis. spectra with ext inctions comparable to those of octaethylporphyrin.