Heptatriene-Fused BIII Subporphyrins

Singly and doubly cycloheptatriene-fused B^III subporphyrins 3 and 6 were synthesized from B^III meso-(2-formylphenyl)-subporphyrin and B^III meso-(2,6-diformylphenyl) subporphyrin, respectively, via a sequence of Wittig methoxymethylenation and acid-catalyzed cyclization. Naphthalene- and benzocycloheptatriene-fused B^III subporphyrin 9 was obtained along with side products 10 and 11 by intramolecular McMurry coupling of B^III 3,7-di(2-formylphenyl)-subporphyrin and subsequent intramolecular oxidative annulation. B^III subporphyrin 9 displays altered optical and electrochemical properties.