Direct alkylation of pyrrole with vinyl substituted aromatics: versatile precursors for the synthesis of porphyrinoid macrocycles

5-Substituted dipyrromethane analogues (8), (23) and (25) were synthesized by the reaction of 2-vinylpyrroles, 2-vinylthiophene or 2-vinylbenzenes with excess pyrrole in the presence of Lewis acids. Accordingly, tripyrromethane analogues could be obtained by starting with 2,5-divinyl thiophene or 2,6-divinylbenzenes. The reaction usually gave moderate yields and catalyst-dependent was seen in some cases. The reaction is compatible with other reported dipyrromethane syntheses and could be applied for the construction of unusual porphyrins.