Cruciform porphyrin pentamers
Abstract
Cruciform porphyrin pentamers 15 and 16 are obtained in good yield by acid-catalyzed tetramerization of ZnII–pyrroloporphyrin 14, followed by oxidation with DDQ; pyrroloporphyrins are in turn obtained from the corresponding pyrrolochlorins by Diels–Alder type reactions of porphyrins involving thermal extrusion of sulfur dioxide from a pyrrole-fused 3-sulfolene.