Synthesis of Subporphyrin Free Bases

Le Liu, Jinseok Kim, Ling Xu, Yutao Rao, Mingbo Zhou, Bangshao Yin, Juwon Oh, Dongho Kim, Atsuhiro Osuka, Jianxin Song

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


BIII subporphyrins are the legitimate ring-contracted porphyrins consisting of three pyrroles and three meso-carbons and their chemistry has been extensively developed since the first synthesis in 2006. However, subporphyrin free bases have never been synthesized, despite tremendous attempts to remove the BIII ion. Here we report that Suzuki–Miyaura coupling between α,α′-diborylated tripyrrane 1 and tetrabromide 5 gave subporphyrin free bases 6, 6 A, and free base dimer 7 in 6 %, 4 %, and 2 % yields as the first examples. Subporphyrin free bases exhibit curved bowl-like structures and distinct 14π-aromaticity. Steady-state and time-resolved spectroscopy revealed that the excited-state behaviors of the subporphyrin free bases are comparable with those of the corresponding BIII subporphyrins. Rotational relaxation processes in the excited states have been revealed, which enhance the electronic interactions with the meso-aryl substituents and between the two subporphyrins.

Original languageEnglish
Article numbere202214342
JournalAngewandte Chemie - International Edition
Issue number50
Publication statusPublished - 2022 Dec 12

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© 2022 Wiley-VCH GmbH.

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry


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