Synthesis of a Phlorin from a Meso-Fused Anthriporphyrin by a Diels-Alder Strategy

An anthracene-containing meso-fused carbaporphyrin, which has extended p-conjugation pathways as compared to the corresponding naphthalene-containing carbaporphyrin, has been synthesized. The weak global aromaticity of the anthriporphyrin also allowed its use as the diene for a Diels-Alder reaction with dimethyl acetylenedicarboxylate (DMAD). The resulting phlorin contains an interesting bicyclic structure. Moreover, to the best of our knowledge, this phlorin is the first Diels-Alder adduct of a diene forming part of the global p-conjugation pathway of an aromatic porphyrinoid.