Synthesis and characterization of meso-tetraphenylporphyrin-corrole unsymmetrical dyads

Flat and gable meso-tetraphenylporphyrin-corrole heterodimers have been syn thesized following a stepwise approach. The macrocyclic precursor for both isomers is a functionalized meso-tetraphenylporphyrin (TPP) bearing a formy l group at one of the peripheral phenyl groups. The preparation of these st arting materials has been improved with respect to the previously reported method. Acidic condensation with pyrrole 8 allows the preparation of a TPP- dipyrromethane intermediate. Subsequent decarboxylation followed by reactio n with formylpyrrole 2 affords the corresponding TPP-a,c-biladiene species. Final cyclization of this intermediate affords the desired heterodimer. At tempts to use the functionalized corrole 5 as starting material were unsucc essful, as this corrole failed to condense with pyrrole and benzaldehyde. T his synthetic approach provides new examples of tetrapyrrolic heterodimers, which can represent useful biomimetic models to study photochemical proces ses. (C) 1998 John Wiley & Sons, Ltd.