Heptagon/Octagon‐Fused Diporphyrins or Spiro‐Pentagon‐Bridged Dichlorin from p‐Terphenylene‐Bridged Diporphyrin

Abstract

AbstractIntramolecular fusion reactions of a p‐terphenylene‐bridged NiII porphyrin dimer gave different products, depending upon reaction conditions. Oxidation with Fe(OTf)3 provided syn‐ and anti‐doubly heptagon‐fused NiII porphyrin dimers showing enlarged π‐electronic networks, probably via a radical mechanism, while treatment with methanesulfonic acid provided a spiro‐pentagon‐bridged NiII chlorin dimer via acid‐catalyzed Friedel‐Crafts type cyclization. Further, a doubly octagon‐fused NiII porphyrin dimer was synthesized via a sequence of double meso‐formylation, reduction to corresponding diol, and BF3‐catalyzed cyclization.