Benziporphyrins

Benziporphyrins are porphyrin analogs containing phenylene subunits in the macrocyclic structure. The first such system, a b-substituted meta-benziporphyrin was reported by Berlin and Breitmaier (Angew. Chem. Int. Ed. Engl. 1994, 33, 1246-1247). We have synthesized a number of meso-aryl macrocycles, including meta- and para-benziporphyrin (1, 2) and A,D-di-para-benzihexaphyrin (3). The aromaticity of these systems has several interesting aspects. Most notably, the expanded macrocycle was the first reported example of a Hückel-Möbius aromaticity switch.