Expanded n-confused phlorin: A platform for a multiply fused polycyclic ring system via oxidation within the macrocycle

Hiroyuki Furuta, Yongshu Xie, Chengjie Li, Qizhao Li, Jiewei Shao, Zhangfa Tong, Masatoshi Ishida, Glib Baryshnikov, Hans Ågren

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22 Citations (Scopus)


Novel interrupted π-conjugated macrocycles derived from expanded porphyrinoids were synthesized, and their unique reactivity was investigated in this work. The specific porphyrin analogs, so-called phlorins and isoporphyrins, possess a meso-sp3 methylene moiety, showing inner 3NH and 1NH pyrrolic cores, respectively, and extended near-infrared (NIR) absorption. Expanded N-confused pentapyrrolic phlorin analog 1 bears an interrupted cyclic π-conjugated system that is featured by a distinct higher HOMO and a lower LUMO. Oxidation of 1 allowed structural transformations through the expanded isoporphyrin-like species 2. One of the representative products is a spiro-carbonbridged multiply N-fused product 3 comprising a fused []- hexacyclic ring obtained by oxidation with 2,3-dichloro-5,6-dicyanop- benzoquinone. When magic blue was used as the oxidant, an aromatic N-confused pentaphyrin 4 was obtained via migration of one of the meso-phenyl groups to the β-position of the neighboring pyrrolic ring. By employing the flexible cavity of 1 for metal coordination, Pd(II) complexation occurred with a specific meso oxygenation to give a bimetallic complex 5. In contrast to the rich oxidation reactions, reduction of 1 with NaBH4 resulted in the regioselective nucleophilic hydrogen substitution reaction at the para position of one of the meso-C6F5 groups. These results provide a practical approach for synthesizing novel interrupted or aromatic π- conjugated frameworks showing NIR absorptions.

Original languageEnglish
Pages (from-to)17195-17205
Number of pages11
JournalJournal of the American Chemical Society
Issue number40
Publication statusPublished - Oct 7 2020

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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