Synthesis of Peripherally Annulated Phenanthroporphyrins

Org Lett. 2023 May 5;25(17):3049-3054. doi: 10.1021/acs.orglett.3c00876. Epub 2023 Apr 25.

Abstract

Synthesis of unusual phenanthroporphyrins was achieved by a stepwise precursor method. Precursor porphyrins fused with aryl-substituted bicyclo[2.2.2]octadiene afforded the corresponding arylbenzoporphyrins (arylBPs) by a retro Diels-Alder reaction. Unusual phenanthroporphyrins were obtained via the intramolecular Scholl reaction of arylBPs. X-ray crystallographic analysis revealed a distorted, helical porphyrin plane. Red-shifted absorptions of tetraphenanthroporphyrin are observed at ca. 580 nm for the B band and at 700-900 nm for the Q bands. Analysis of magnetic circular dichroism spectra and time-dependent density functional theory calculations was used to explain the optical properties and electronic structures.