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

Kenta Kato; Yasutomo Segawa; Lawrence T. Scott; Kenichiro Itami

doi:10.1002/anie.201711985

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

Kenta Kato, Yasutomo Segawa, Lawrence T. Scott, Kenichiro Itami

Research output: Contribution to journal › Article › peer-review

47 Citations (Scopus)

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 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.

Original language	English
Pages (from-to)	1337-1341
Number of pages	5
Journal	Angewandte Chemie - International Edition
Volume	57
Issue number	5
DOIs	https://doi.org/10.1002/anie.201711985
Publication status	Published - 2018 Jan 26
Externally published	Yes

Keywords

arenes
corannulenes
helicenes
polycycles

ASJC Scopus subject areas

Catalysis
Chemistry(all)

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title = "A Quintuple [6]Helicene with a Corannulene Core as a C5-Symmetric Propeller-Shaped π-System",

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 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.",

keywords = "arenes, corannulenes, helicenes, polycycles",

author = "Kenta Kato and Yasutomo Segawa and Scott, {Lawrence T.} and Kenichiro Itami",

note = "Funding Information: This work was supported by the ERATO program from JST (JPMJER1302 to K.I.), the Funding Program for KAKENHI from MEXT (JP16K05771 to Y.S.), a grant-in-aid for Scientific Research on Innovative Areas “p-Figuration” from JSPS (JP17H05149 to Y.S.), the Noguchi Institute (to Y.S.), and the US National Science Foundation (CHE-1149096 to L.T.S.). K.K. thanks IGER Program in Green Natural Sciences, Nagoya University and a JSPS fellowship for young scientists. Calculations were performed using the resources of the Research Center for Computational Science, Okazaki, Japan. ITbM is supported by the World Premier International Research Center Initiative (WPI), Japan. Publisher Copyright: {\textcopyright} 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.",

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AU - Kato, Kenta

AU - Segawa, Yasutomo

AU - Scott, Lawrence T.

AU - Itami, Kenichiro

N1 - Funding Information: This work was supported by the ERATO program from JST (JPMJER1302 to K.I.), the Funding Program for KAKENHI from MEXT (JP16K05771 to Y.S.), a grant-in-aid for Scientific Research on Innovative Areas “p-Figuration” from JSPS (JP17H05149 to Y.S.), the Noguchi Institute (to Y.S.), and the US National Science Foundation (CHE-1149096 to L.T.S.). K.K. thanks IGER Program in Green Natural Sciences, Nagoya University and a JSPS fellowship for young scientists. Calculations were performed using the resources of the Research Center for Computational Science, Okazaki, Japan. ITbM is supported by the World Premier International Research Center Initiative (WPI), Japan. Publisher Copyright: © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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Y1 - 2018/1/26

N2 - 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.

AB - 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.

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