Porphyrins with β,β'-fused five-membered rings

Abstract

Recent studies involving porphyrin systems bearing fused five-membered rings are reviewed, these including pyrrolo[3,4-b]porphyrins and fused metallocenoporphyrins. Diels-Alder cycloadditions between pyrroloporphyrins, to give benzoporphyrins, are discussed. The syntheses of mono-, and the two regioisomers (adj- and opp-) of bis-sulfolenoporphyrins are then discussed and their reactions with dienophiles such as dimethyl acetylenedicarboxylate are outlined.