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A Möbius Aromatic [28]Hexaphyrin Bearing a Diethylamine Group: A Rigid but Smooth Conjugation Circuit
Author(s) -
Higashino Tomohiro,
Soya Takanori,
Kim Woojae,
Kim Dongho,
Osuka Atsuhiro
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201500099
Subject(s) - diethylamine , chemistry , antiaromaticity , aromaticity , triethylamine , molecule , metalation , stereochemistry , organic chemistry
The reaction of [26]hexaphyrin with triethylamine in the presence of BF 3 ⋅OEt 2 and O 2 furnished a diastereomeric mixture of a diethylamine‐bearing [28]hexaphyrin as a rare example of a Möbius aromatic metal‐free expanded porphyrin. The Möbius aromaticity of these molecules is large, as indicated by their large diatropic ring currents, which are even preserved at 100 °C, owing to their internally multiply bridged robust structure with a smooth conjugation network. These molecules were reduced with NaBH 4 to give an antiaromatic [28]hexaphyrin, and were oxidized with MnO 2 to give aromatic [26]hexaphyrins, both through a Möbius‐to‐Hückel topology switch induced by a CN bond cleavage.