MacDonald [2+2]-type condensation with vicinal diketones: Synthesis and properties of novel spiro-tricyclic porphodimethenes

[GRAPHICS] Acid catalyzed [2 + 2] condensation reactions of polycyclic aromatic vicina l diketones including aceanthrenequinone, phenathrenequinone, and pyrene-4, 5-dione with 5-mesityldipyrromethanes are outlined, and this methodology pr ovides a flexible entry to spiro-tricyclic porphodimethenes, The porphodime thene products have been fully characterized, including X-ray structure ana lyses and fluorescence spectroscopy. In the case of the phenanthrenone subs tituted macrocycle, the two spiro-locks can be ring-opened to form a trans- bis(2 '- hydroxymethylbiphenyl) substituted porphyrin.