Ly. Xie et D. Dolphin, A NEW APPROACH TO THE AROMATIC MACROCYCLE PORPHOCYANINE, Journal of the Chemical Society, Chemical Communications, (12), 1994, pp. 1475-1476
Treatment of 3,3',4,4'-tetraalkyl-5,5'-bisformyldipyrromethanes with a
mmonia leads directly to the formation of an expanded tetrapyrrolic ar
omatic macrocyclic compound, porphocyanine.