Synthesis of Porphyrin Dimers Fused with a Benzene Unit

Bicyclo[2.2.2]octadiene‐connected pyrrolo‐porphyrins have been prepared by an inverse‐type [3+1] porphyrin synthesis of a bicyclo[2.2.2]octadiene‐fused dipyrrole with a tripyrrane dicarbaldehyde. Another [3+1] porphyrin synthesis of pyrrole‐connected porphyrins with the same or other tripyrrane dicarbaldehydes gave bicyclo[2.2.2]octadiene‐bridged diporphyrins, the central metals and/or peripheral substituents of which were different. Thermal decomposition of the bicyclo[2.2.2]octadiene skeleton to a benzene moiety gave π‐system‐fused porphyrin dimers in a highly pure form.