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A Robust Porphyrin‐Stabilized Triplet Carbon Diradical
Author(s) -
Wang Kaisheng,
Liu Pingting,
Zhang Fenni,
Xu Ling,
Zhou Mingbo,
Nakai Akito,
Kato Kenichi,
Furukawa Ko,
Tanaka Takayuki,
Osuka Atsuhiro,
Song Jianxin
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202015356
Subject(s) - diradical , porphyrin , chemistry , anthracene , photochemistry , radical , intramolecular force , naphthalene , polymer chemistry , singlet state , organic chemistry , physics , nuclear physics , excited state
The synthesis of robust high‐spin carbon radicals is an important topic in organic chemistry. Toward this end, several porphyrin‐stabilized radicals have been systematically explored. A singly naphthalene‐fused porphyrin radical was synthesized by a reaction sequence consisting of a Suzuki–Miyaura coupling of β‐borylated porphyrin with 2‐bromobenzaldehyde, addition of mesityl Grignard reagent, intramolecular Friedel–Crafts alkylation, and final oxidation with DDQ or t BuOK/O 2 . This strategy was also used to synthesize doubly naphthalene‐fused porphyrins and syn ‐ and anti ‐fused‐anthracene‐bridged porphyrin dimers. While singly naphthalene‐fused porphyrin radical has been shown to be a stable monoradical, doubly naphthalene‐fused porphyrins and anti ‐fused‐anthracene‐bridged porphyrin dimers have been shown to be closed‐shell molecules. Finally, the syn ‐dimer was characterized as a surprisingly stable radical ( t 1/2 =28 days under ambient air and at 80 °C) that is storable for more than several months, despite its high‐spin triplet ground‐state carbon diradical.