A convergent approach to unsymmetrical porphyrin oligomers

Unsymmetrical capped porphyrin dimers are prepared by coupling two alkynyl monomer units to a central core, followed by intramolecular cyclisation of the alkynes; the approach is illustrated by the synthesis of an unsymmetrical trimer with a ‘small’ cavity and of a dimer equipped with a chiral binaphthyl cap.