Premium
A Quintuple [6]Helicene with a Corannulene Core as a C 5 ‐Symmetric Propeller‐Shaped π‐System
Author(s) -
Kato Kenta,
Segawa Yasutomo,
Scott Lawrence T.,
Itami Kenichiro
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201711985
Subject(s) - helicene , corannulene , chemistry , racemization , chirality (physics) , moiety , crystallography , intramolecular force , enantiomer , stereochemistry , molecule , organic chemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark
Abstract 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 C 5 ‐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.