Conversion of Meso-Aryl Substituted Open-Chain Pentapyrroles to Sapphyrins: Synthesis and Electrochemistry

Abstract

Sapphyrin is a 22-π aromatic pentapyrrolic macrocycle containing one direct link and four bridging methine groups between five pyrrole subunits.1 This macrocycle is an early member of the group of “expanded porphyrins” and was obtained from a pentapyrrole, a byproduct in the synthesis of corroles. A series of open-chain pentapyrroles and sapphyrins with meso-tetraaryl groups were synthesized (Figure 1) and are characterized as to their electrochemistry and protonation reactions in nonaqueous media.2 The protonation-initiated conversion of pentapyrroles to sapphyrins upon oxidation was investigated and cyclic voltammetry was used to measure the redox potentials in CH2Cl2, PhCN, and/or pyridine (Py).REFERENCES1. V. J. Bauer, D. L. J. Clive, D. Dolphin, J. B. Paine, F. L. Harris, M. M. King, J. Loder, S. W. C. Wang, R. B. Woodward, J. Am. Chem. Soc. 1983, 105,6429-6436.2. W. Shan, N. Desbois, V. Blondeau-Patissier, M. L. Naitana, V. Quesneau, C. P. Gros, Y. Rousselin, W. Huang, Z. Ou, K. M. Kadish, Chem. Eur. J., 2017 , 23, 12833-12844.Figure 1 Figure 1