Substituent-controlled construction of A(4)B(2)-hexaphyrins and A(3)B-porphyrins: a mechanistic evaluation.

A substituent-dependent construction of novel A(3)B-porphyrins along with A(4)B(2)-hexaphyrins was realized by the reactions of N-tosylimines and meso-aryl-substituted tripyrranes in the presence of Cu(OTf)(2) as the catalyst. The reaction mechanism of the presented method was studied on model reactions by electrospray-ionization time-of-flight (HRESI-TOF) mass spectral analysis in a timely manner. The analytical results indicated that the observed azafulvene-ended di- and tripyrrolic intermediates are responsible for the formation of porphyrinogen and hexaphyrinogen forms.