A Modified Pyrrole Biscarbinol Approach to Opp-A2B2-Symmetric Benzoporphyrins

ChemistryEurope 2026, 4, e202500297.

In the pursuit of advanced functional materials, π-extended porphyrin derivatives, particularly β,β-benzannulated tetrapyrroles, have garnered significant attention due to their unique structural and electronic properties. This study refines existing methodologies for the selective synthesis of opp-A₂B₂-symmetric benzoporphyrins based on 4,7-dihydro-4,7-ethano-2H-isoindole or [3,4]epipyrroloanthracene building blocks. By condensation of preformed biscarbinols, this approach overcomes regioselectivity challenges in traditional condensation methods, which typically favor other isomers over the desired opp-A₂B₂ regio derivative. The analysis of the resulting C_2v-symmetric tetrapyrroles exhibit distinct optoelectronic, electrochemical, and structural properties compared to their fully symmetrical A₄ counterparts, underscoring their potential in organic optoelectronics applications.