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Reversible Redox Reaction Between Antiaromatic and Aromatic States of 32π‐Expanded Isophlorins
Author(s) -
Gopalakrishna Tullimilli Y.,
Anand Venkataramanarao G.
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201403372
Subject(s) - antiaromaticity , chemistry , furan , ring (chemistry) , redox , thiophene , reactivity (psychology) , aromaticity , triethylamine , crystallography , oxidation state , photochemistry , stereochemistry , computational chemistry , organic chemistry , molecule , catalysis , medicine , alternative medicine , pathology
32π‐antiaromatic expanded isophlorins with a varying number of thiophene and furan rings adopt either planar, ring‐inverted, or twisted conformations depending on the number of furan rings in the macrocycle. However, they exhibit identical reactivity with respect to their oxidation to aromatic 30π‐dicationic species under acidic conditions. These 32π‐antiaromatic macrocycles can also be oxidized with [Et 3 O + SbCl 6 − ]and NOBF 4 to generate dications, thus confirming ring oxidation of macrocycles. Furthermore, they can be reduced back to their parent 32π‐antiaromatic state by triethylamine, Zn, or FeCl 2 . Single‐crystal X‐ray diffraction analysis confirmed a figure‐eight conformation for a hexafuran system, which opens to a planar structure upon oxidation.