A Quintuple [6]Helicene with a Corannulene Core as a C5‐Symmetric Propeller‐Shaped π‐System

The synthesis and structural analysis of a quintuple [6]helicene with a corannulene core is reported. The compound was synthesized from corannulene in three steps including a five‐fold intramolecular direct arylation. X‐ray crystallographic analysis revealed a C5‐symmetric propeller‐shaped structure...

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Bibliographic Details
Published in:Angewandte Chemie 2018-01, Vol.130 (5), p.1351-1355
Main Authors: Kato, Kenta, Segawa, Yasutomo, Scott, Lawrence T., Itami, Kenichiro
Format: Article
Language:eng ; ger
Subjects:
Arene
Chemistry
Chirality
Corannulene
Crystallography
Enantiomers
Helicene
High-performance liquid chromatography
Inversion
Liquid chromatography
Polycyclen
Racemization
Spectroscopy
Structural analysis
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Summary:The synthesis and structural analysis of a quintuple [6]helicene with a corannulene core is reported. The compound was synthesized from corannulene in three steps including a five‐fold intramolecular direct arylation. X‐ray crystallographic analysis revealed a C5‐symmetric propeller‐shaped structure and one‐dimensional alignment in the solid state. The enantiomers of the quintuple [6]helicene were successfully separated by HPLC, and the chirality of the two fractions was identified by CD spectroscopy. A kinetic study yielded a racemization barrier of 34.2 kcal mol−1, which is slightly lower than that of pristine [6]helicene. DFT calculations indicate a rapid bowl‐to‐bowl inversion of the corannulene moiety and a step‐by‐step chiral inversion pathway for the five [6]helicene moieties. Ein fünfblättriger Propeller: Das fünffache [6]Helicen 1 mit Corannulen‐Kern wurde synthetisiert. Eine Röntgen‐Strukturanalyse bestätigte die C5‐symmetrische propellerförmige Struktur von 1. DFT‐Rechnungen ergeben eine schnelle Schale‐zu‐Schale‐Inversion der Corannulen‐Einheit und eine schrittweise Chiralitätsinversion der fünf [6]Helicen‐Einheiten.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201711985