Contracted Porphyrins: Octaethylisocorrole

The most stable of the three possible structural isomers of corrole is, according to theory, isocorrole, for which the title compound 1 is a model compound. The reductive McMurry coupling of the corresponding α,ω-tetrapyrroledialdehyde affords an entry to 1. The isocorrole derivative 1 has, like corrole, the propensity to stabilize metals in high oxidation states. This is exemplified by the CuIII complex 2, which has been isolated as an intermediate in the synthesis of 9-formyloctaethylisocorrole.