A strategy for the stepwise ring annulation of all four pyrrolic rings of a porphyrin

The repeated introduction of an a-dione unit and its reaction with an arene-1,2-diamine allows the stepwise annulation of all four pyrrolic rings of a porphyrin, as is demonstrated by the synthesis of a trisquinoxalinoporphyrin, a tetrakisquinoxalinoporphyrin and the more elaborated bisporphyrin.