Retro‐Diels–Alder Approach to the Synthesis of π‐Expanded Azuliporphyrins and Their Porphyrinoid Aromaticity |
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| Authors: | Prof Dr Tetsuo Okujima Tasuku Kikkawa Prof Dr Haruyuki Nakano Hiroshi Kubota Nobumasa Fukugami Prof Dr Noboru Ono Prof Dr Hiroko Yamada Prof Dr Hidemitsu Uno |
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| Institution: | 1. Graduate School of Science and Engineering, Ehime University, Matsuyama 790‐8577 (Japan), Fax: (+81)?89‐927‐9615;2. Graduate School of Sciences, Kyushu University, Fukuoka 812‐8581 (Japan);3. Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma 630‐0192 (Japan) |
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| Abstract: | Bicyclo2.2.2]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. |
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| Keywords: | ab initio calculations cations conjugation electronic structure porphyrinoids |
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