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Retro‐Diels–Alder Approach to the Synthesis of π‐Expanded Azuliporphyrins and Their Porphyrinoid Aromaticity
Author(s) -
Okujima Tetsuo,
Kikkawa Tasuku,
Nakano Haruyuki,
Kubota Hiroshi,
Fukugami Nobumasa,
Ono Noboru,
Yamada Hiroko,
Uno Hidemitsu
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201201399
Subject(s) - aromaticity , diels–alder reaction , benzene , porphyrin , chemistry , computational chemistry , chemical shift , bicyclic molecule , photochemistry , stereochemistry , organic chemistry , molecule , catalysis
Bicyclo[2.2.2]octadiene (BCOD) fused azuliporphyrins were synthesized by 3+1 porphyrin synthesis of azulitripyrranes with diformylpyrroles. Subsequent retro‐Diels–Alder reaction of the BCOD‐fused azuliporphyrins afforded azulibenzo‐, azulidibenzo‐, and azulitribenzoporphyrins 1 – 5 . NMR and UV/Vis spectra, as well as nucleus‐independent chemical shift (NICS) calculations revealed that 1 – 5 and their diprotonated dications exhibit relatively low porphyrinoid aromaticity, which was dependent on the position and number of fused benzene rings present.