Anomalous Double Cyclization reactions of beta-formylporphyrins
Barloy, L., Dupre, D., Wijesekera, T., and David Dolphin
J. Org. Chem.,
Treatment of Ni(II) and Cu(II) complexes of 2(β)-formyl-meso-tetraphenylporphyrins with strong acid results in intramolecular cyclization involving the carbonyl C and the ortho-Ph position leading to naphthoporphyrin derivatives. However, when electron-releasing groups are present at the m-Ph positions, a 2nd cyclization occurs involving the 3(β) position and the ortho position of the adjacent Ph ring to give an additional fused ring.